Connected Cruise Control Vehicle Research Articles

State-Estimation-Based Control Strategy Design for Connected Cruise Control With Delays

The research on connected and automated vehicles attracts much attention recently. In connected vehicle systems, connected cruise control (CCC) is a wildly concerned technique to improve traffic safety and mitigate congestion. In this article, an optimal state-estimation-based (SE-based) control algorithm is proposed in a backward recursion manner to regulate CCC vehicle's longitudinal motion under stochastic communication delays, state noises, and channel interferences. Based on the analysis of error dynamics of vehicles and optimal state estimation strategy, the SE-based system dynamics is first formulated by using the Kalman filtering method. Then, a two-step SE-based control algorithm aiming at minimizing the quadratic system cost is proposed to enhance the vehicular platoon stability. In particular, the optimal control strategy can be generated online as a linear function of the estimated state information and previous control signals, and the corresponding coefficient can be iteratively calculated in an offline step. Finally, the results are successfully extended to the case of arbitrary communication delays, and the condition for the asymptotically mean square stability of the proposed optimal SE-based CCC algorithm is derived. Simulation results indicate that the proposed SE-based control algorithm has better system performance and control stability compared with existing works.

Robust Control of Connected Cruise Vehicle Platoon With Uncertain Human Driving Reaction Time

Connected cruise control (CCC), as an advanced driver assistance system (ADAS), can enhance the stability and safety of the traffic flow. It is worth noting that the uncertain human driving reaction time will seriously affect the stability of the entire CCC system. In this paper, the car-following platoon is considered, where the CCC autonomous vehicle at the tail receives velocity and position signals of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n$</tex-math></inline-formula> human-driven vehicles ahead through wireless vehicle-to-vehicle (V2V) communication. A robust feedback controller is designed by only using the current states of each preceding vehicle and the ego vehicle based on the LaSalle-Yoshizawa-like condition to overcome the influence of uncertain human driving reaction time. The Lyapunov-Razumikhin approach analyzes the stability of the CCC vehicle in the closed-loop system, and the string stability of the whole CCC system is ensured by dissipativity with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$L_2$</tex-math></inline-formula> gain. The practicability of the designed robust controller is verified by simulation comparison with other design schemes.

Car-following Model of Connected Cruise Control Vehicles to Mitigate Traffic Oscillations

With the aim of mitigating traffic oscillations, this paper extends a car-following model for Connected Cruise Control (CCC) systems by considering electronic throttle angles of multiple cars ahead. The linear stability condition of the proposed model is derived and numerical simulations are performed. It has been found that the proposed model is prominently better than the previous model, i.e. full velocity difference model, from the perspective of mitigating traffic oscillations. Additionally, the proposed model can also reduce fuel consumption, emissions, i.e. CO, HC and NOX, safety risk, and improve driving comfort at the same time. Simulation results suggest that the CCC car-following control design should consider the effect of multiple electronic throttle angles from the preceding cars.

Optimal Connected Cruise Control With Arbitrary Communication Delays

Connected cruise control (CCC), as an approach to regulate vehicle’s longitudinal motion in car-following platoon scenarios, can improve the safety and efficiency of the traffic flow. In order to make it available for extensive information sharing among vehicles, wireless vehicle-to-vehicle (V2V) communication is exploited in the vehicular platoon. However, time delays caused by wireless communication may result in significant degradation of system stability. In this article, considering arbitrary V2V communication delays, an optimal longitudinal control algorithm is proposed for the CCC vehicle with the goal of minimizing the deviations of vehicle’s headway and velocity. In the proposed scheme, the vehicular platoon is modeled as a discrete-time system based on vehicle’s error dynamics, and the optimal-state feedback control problem is designed as a cost function represented by a sum of platoon states in a quadratic form. A backward recursion method is used to iteratively derive the optimal control strategy, namely the acceleration for CCC vehicle, based on the current platoon states and previous control signals. In addition, the stability analysis shows that the system is asymptotically mean square stable under the control of the proposed algorithm. Finally, numerical simulations indicate that the proposed algorithm provides better system performance and stability.

A Cruise Control Method for Connected Vehicle Systems Considering Side Vehicles Merging Behavior

On the basis of wireless vehicle-to-vehicle communication, this paper proposes a superior control strategy for the merging behavior of connected cruise control (CCC) considering the effect of time delays. A novel range policy that integrates the consideration of side-vehicle merging scene is established, based on which a general strategy is proposed focusing on the acceleration control and incorporating various information delays. In this portion, the time-delay effect for the plant stability and head-to-tail string stability of CCC is explored and analyzed in detail. The results demonstrate that the traffic efficiency, the driving safety, and the ride comfort of CCC vehicles can be improved by the proposed method. In addition, the sensitivity study regarding the controller gain and the platoon’s connectivity structure is exploited, which is proved to be of importance for system stability.

Control design for stable connected cruise control systems to enhance safety and traffic efficiency

To enhance safety and traffic efficiency, stability of a mixed human and connected cruise control (CCC) system is studied. The authors consider individual vehicle platoons, in which the tail CCC vehicle receives feedback from multiple human-driven vehicles ahead via vehicle-to-vehicle communications, with the objective of stability analysis and feedback control design. To deal with this, the transfer function theory is used. Simulations are also performed to evaluate impacts of the mixed human and CCC system on safety and traffic efficiency. Results show that the output bounds of the CCC feedback coefficients can be appropriately designed to keep local individual vehicle platoons stable for all possible vehicle speeds. The feedback coefficient has a larger design range and the required lower bound value decreases as the feedback length increases. Additionally, the system design would improve traffic safety and efficiency even at lower CCC vehicle penetration rates.

Optimal Control of Connected Vehicle Systems With Communication Delay and Driver Reaction Time

In this paper, linear quadratic regulation is used to obtain an optimal design of connected cruise control (CCC). We consider vehicle strings where a CCC vehicle receives position and velocity signals through wireless vehicle-to-vehicle communication from multiple vehicles ahead. Communication delay, driver reaction time, and heterogeneity of vehicles are considered. The optimal feedback law is obtained by minimizing a cost function defined by headway and velocity errors and the acceleration of the CCC vehicle on an infinite horizon. We show that, by decomposing the optimization problem, the feedback gains can be obtained recursively as signals from vehicles farther ahead become available, and that the gains decay exponentially with the number of cars between the source of the signal and the CCC vehicle. Such properties allow graceful degradation of CCC performance under imperfect communication. The effects of the cost function on the head-to-tail string stability are also investigated and the robustness against variations in human parameters is tested. The analytical results are verified by numerical simulations at the nonlinear level. The results allow us to significantly reduce the complexity of CCC design.

Motif-Based Design for Connected Vehicle Systems in Presence of Heterogeneous Connectivity Structures and Time Delays

In this paper, we investigate the effects of heterogeneous connectivity structures and information delays on the dynamics of connected vehicle systems (CVSs), which are composed of vehicles equipped with connected cruise control (CCC) as well as conventional vehicles. First, a general framework is presented for CCC design that incorporates information delays and allows a large variety of connectivity structures. Then, we present delay-dependent criteria for plant stability and head-to-tail string stability of CVSs. The stability conditions are visualized by using stability diagrams, which allow one to evaluate the robustness of vehicle networks against information delays. To achieve modular and scalable design of large networks, we also propose a motif-based approach. Our results demonstrate the advantages of CCC vehicles in improving traffic efficiency, but also show that increasing the penetration of CCC vehicles does not necessarily improve the robustness if the connectivity structure or the control gains are not appropriately designed.

Optimized connected cruise control with time delay

In this paper, we optimize the connectivity structure for connected cruise control (CCC) using linear quadratic regulation (LQR) while taking into account driver reaction time delay. We consider that a CCC-equipped vehicle receives position and velocity signals through wireless vehicle-to-vehicle (V2V) communication from multiple vehicles ahead and minimize a cost function defined by headway and velocity errors and the acceleration of the CCC vehicle over an infinite horizon. The resulting optimal feedback contains distributed delay. We show that the feedback gains and the distribution kernels can be obtained recursively as signals from vehicles farther ahead become available. Moreover, the gains exhibit exponential decay as the number of cars between the source and the CCC vehicle increases. The performance of the developed CCC controller is verified by numerical simulations.

Dynamics of connected vehicle systems with delayed acceleration feedback

In this paper, acceleration-based connected cruise control (CCC) is proposed to increase roadway traffic mobility. CCC is designed to be able to use acceleration signals received from multiple vehicles ahead through wireless vehicle-to-vehicle (V2V) communication. We consider various connectivity structures in heterogeneous platoons comprised of human-driven and CCC vehicles. We show that inserting a few CCC vehicles with appropriately designed gains and delays into the flow, one can stabilize otherwise string unstable vehicle platoons. Exploiting the flexibility of ad-hoc connectivity, CCC can be applied in a large variety of traffic scenarios. Moreover, using acceleration feedback in a selective manner, CCC provides robust performance and remains scalable for large systems of connected vehicles. Our conclusions are verified by simulations at the nonlinear level.