Sampled-data distributed control for mixed traffic flow with unknown disturbance

Stability analysis and connected vehicles management for mixed traffic flow with platoons of connected automated vehicles

The information interaction characteristics of connected vehicles are distinct from those of non-connected vehicles, thereby exerting an influence on the conventional traffic flow model. The original lane-changing model for non-connected vehicles is no longer applicable in the context of the new traffic flow environment. The modelling of the new hybrid traffic flow, comprising both connected and ordinary vehicles, is set to be a pivotal research topic in the coming years. The objective of this paper is to present a methodology for optimal mixed traffic flow dynamic modelling and cooperative control in intelligent and connected environments (ICE). The study utilizes the real-time perception and information interaction of connected vehicles for traffic information, taking into account the access characteristics of both connected and non-connected vehicles. The satisfaction-based free lane-changing and mandatory lane-changing models of connected vehicles are designed. Secondly, a mixed traffic flow lane-changing model based on influence characteristics is constructed for the influence area of connected vehicles. This model takes into account the degree of influence that connected vehicles have on non-connected vehicles, with different distances being considered respectively. Subsequently, a vehicle guidance strategy for mixed traffic flows comprising grid-connected and conventional vehicles is proposed. A variety of speed guidance scenarios are considered, with an in-depth analysis of the speed optimization of connected vehicles and the movement law of non-connected vehicles. This comprehensive analysis forms the foundation for the development of a vehicle guidance strategy for mixed traffic flows, with the overarching objective being to minimize the average delay of vehicles. In order to evaluate the effectiveness of the proposed method, the intersection of Gaota Road and Fangshui North Street in Yanqing District, Beijing, has been selected for analysis. The results of the study demonstrate that by modifying the density of the mixed traffic flow, the overall average speed of the mixed traffic flow declines as the density of vehicles increases. The findings reported in this study reflect the role of connected vehicles in enhancing road capacity, maximizing intersection capacity and mitigating the occurrence of queuing phenomena, and improving travel speed through the mixed traffic flow lane-changing model based on impact characteristics. This study also provides some guidance for future control of the mixed traffic flow formed by emergency vehicles and social vehicles and for realizing a smart city.

This study aims to analyze the impact of connected and autonomous vehicles (CAVs) on traffic flow under various penetration rates. Based on a recently proposed heterogeneous flow model, the mixed traffic flow with both conventional vehicles and CAVs was simulated and studied. Acceleration rate and velocity distributions of the mixed traffic flow were presented to show the evolution of mixed traffic flow dynamics with the increase in CAV penetration rate within the mixed flow. Spatiotemporal diagrams of mixed traffic flow were presented to show the effect of CAVs on damping the stop-and-go traffic flow. Results show that with the increase in CAV penetration rate, the portion of smooth driving is increased. Velocity difference between vehicles is decreased and traffic flow is greatly smoothed. Stop-and-go traffic will be greatly eased when CAV penetration rate reaches a rate of 40%∼50%. More cautious following strategy of the CAV would contribute to a greater benefit on traffic safety. This work provides some insights into the impact of the CAV on traffic flow and sheds light on how would the mixed traffic flow dynamics evolve with the gradual adoption of CAV under current traffic system.

With the emerging application of low-level driving automation technology, heterogeneous traffic flow mixed with human-driven vehicles and low-level autonomous vehicles is dawning. In this context, it is imperative to investigate its effect on mixed traffic flow. As a key component for adaptive cruise control (ACC) which is a practical low-level application of driving automation, the time gap policy determines the dynamic of ACC-equipped vehicles and plays a crucial role in traffic flow stability and efficiency. There are two main time gap policies used for ACC at present, namely, constant time gap (CTG) policy and variable time gap (VTG) policy. In this study, we carried out a detailed comparison between these time gap policies to investigate their potential effect on mixed traffic flow, where the analytical- and simulation-based approaches are both considered. Analytical results show that VTG policy is superior to CTG policy in stabilizing the mixed traffic flow. In addition, numerical simulations are also conducted and simulation results further support the analytical results. As for throughput, there is no difference between CTG policy and VTG policy in analytical progress when the same time gap is set at the equilibrium. However, simulation results based on an on-ramp scenario show that the throughput of mixed traffic flow with VTG policy is slightly higher than that of CTG policy. Meanwhile, the scatter of mixed traffic flow with VTG policy in the flow-density diagram gradually clusters in the middle range of density (i.e., 20–40 veh/km) with the increase of the penetration rates of ACC vehicles, where the traffic flow operates more efficiently. These results indicate that VTG policy is better than CTG policy when designing controllers for ACC in the context of traffic flow operation and control.

Microscopic state evolution model of mixed traffic flow based on potential field theory

PurposeThe purpose of this paper is to explore the impact of the mixed traffic flow, self-stabilization effect and the lane changing behavior on traffic flow stability.Design/methodology/approachAn extended two-lane lattice hydrodynamic model considering mixed traffic flow and self-stabilization effect is proposed in this paper. Through linear analysis, the stability conditions of the extended model are derived. Then, the nonlinear analysis of the model is carried out by using the perturbation theory, the modified Kortweg–de Vries equation of the density of the blocking area is derived and the kink–antikink solution about the density is obtained. Furthermore, the results of theoretical analysis are verified by numerical simulation.FindingsThe results of numerical simulation show that the increase of the proportion of vehicles with larger maximum speed or larger safe headway in the mix flow are not conducive to the stability of traffic flow, while the self-stabilization effect and lane changing behavior is positive to the alleviation of traffic congestion.Research limitations/implicationsThis paper does not take into account the factors such as curve and slope in the actual road environment, which will have more or less influence on the stability of traffic flow, so there is still a certain gap with the real traffic environment.Originality/valueThe existing two-lane lattice hydrodynamic models are rarely discussed in the case of mixed traffic flow. The improved model proposed in this paper can better reflect the actual traffic, which can also provide a theoretical reference for the actual traffic governance.

This note studies the asymptotic regulation problem for a class of nonholonomic systems with unknown constant disturbances, where system nonlinearities admit a lower-triangular form. First, following a new state transformation, the considered systems with unknown constant disturbances are converted into a class of auxiliary systems without disturbances. Second, two sampled-data controllers are designed for the auxiliary systems by using the high-gain method. Third, it is shown that with the introduced state transformation, the desired sampled-data <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">integral</i> controllers are obtained to asymptotically regulate the considered systems. The proposed control strategy is applied to asymptotically regulate a unicycle type mobile robot model.

Method for utilizing the reserved lane capacity: Formation of the mixed traffic flow

Evaluating the impact of connected and autonomous vehicles on traffic safety

With the development of intelligent connected vehicles (ICVs) and communication technology, collaborative operation among vehicles will become the trend of the future. Thus, traffic flow will be mixed with manual driving vehicles and ICVs. A mixed traffic flow is a traffic flow state lying between autonomous and manual traffic flows. In order to describe the car-following characteristics in a mixed traffic flow, the cooperative adaptive cruise control (CACC) car-following model and the intelligent driver model (IDM) were adopted. The car-following characteristics of different platoons from these two car-following models were analyzed. The CACC mixing ratio was used to describe the mixed traffic flow. The fixed states and disturbance states of the car-following platoons were simulated. The fixed states can be divided into three categories: the steady state, acceleration state, and deceleration state. The effects of different car-following cases and different mixing ratios on mixed traffic flow in different states were discussed. The results show that (1) in the steady state with a smaller mixing ratio, the operating speed and traffic volume of the mixed traffic flow were positively correlated. The overall traffic volume decreased with the increase in the mixing ratio, and the gap gradually narrowed. At a larger mixing ratio, the operating speed and traffic volume were negatively correlated. The overall traffic volume increased with the increase in the mixing ratio. (2) In the acceleration state, the maximum traffic volume in the platoon and the optimal mixing ratio were linearly related to the acceleration. (3) In the deceleration state with a fixed mixing ratio, the traffic volume decreased with the increase in the deceleration, with slight differences in the changing trend of the volume of the mixed flow. Under disturbances, the mixed traffic volume was positively correlated with the mixing ratio, i.e., at a larger mixing ratio, the anti-interference ability of the mixed traffic flow was higher.

Modeling and analysis of mixed traffic flow capacity and stability considering human-driven vehicle drivers' trust attitude towards intelligent connected vehicles

With the increase of citizens' income and the expansion of cities, previous bicycle traffic has been transferred to moped traffic gradually in Chinese metropolis. Moped Vehicle is bigger, heavier and faster than a bicycle. However, since moped vehicles traveled along with bicycle vehicles in the same non-motor traffic lanes, some problems arise, such as lane capacity reduction and traffic accidents addition. On the basis of abundant investigation data and information collection, diversified methods, such as literature analysis, summary, mathematical statistics and so on, were applied to model mixed traffic flow in the paper. Meanwhile, based on the research of mixed traffic flow model and the theory of standard vehicle equivalent coefficient, the paper conducted related research on the standard moped equivalent and finally came to the equivalent value of big and small mopeds equal to bicycles in the specific mixed traffic flow. The result provided support for non-motor traffic design, moped traffic management and related policies for the ongoing study. Keywords Moped vehicle traffic, Mixed traffic flow, Traffic flow model, Standard Vehicle Equivalent

On the assessment of the dynamic platoon and information flow topology on mixed traffic flow under connected environment

This paper focuses on traffic scenarios randomly mixed with cooperative adaptive cruise control (CACC) vehicles and manual vehicles with vehicle-to-vehicle (V2V) communication. The analytical investigation of string stability of such mixed traffic flow is conducted under different CACC penetration rates. The parametric sensitivity analysis on CACC desired time-gap is also studied. Moreover, numerical simulation is conducted under both open and periodic boundary conditions. Research results indicate that increase of CACC vehicles is helpful for improving the mixed traffic flow string stability. The mixed flow will be stable for all possible velocities if CACC rate reaches to 0.64 when the CACC time-gap is considered as 0.6s. Larger CACC time-gap would have more stable regions in string stability charts with respect to equilibrium velocity and CACC penetration rate. This paper contributes to a new way for analytical investigation of string stability of the mixed CACC traffic flow.

Linear internal stability for mixed traffic flow of CAVs with different automation levels