The effect of the information delay, which was caused by thc naturc of the distance sensors and wireless communication systems, on the string stability of platoon of automated vehicles was studied. The longitudinal ve...The effect of the information delay, which was caused by thc naturc of the distance sensors and wireless communication systems, on the string stability of platoon of automated vehicles was studied. The longitudinal vehicle dynamics model was built by taking the information delay into consideration, and three typical information frameworks, i.e., leader-predecessor framework （LPF）, multiple-predecessors framework （MPF） and predecessor-successor framework （PSF）, were defined and their related spacing error dynamics models in frequency domain were proposed. The string stability of platoon of automated vehicles was analyzed for the LPF, MPF and PSF, respectively. Meanwhile, the related sufficient string stable conditions were also obtained. The results demonstrate that the string stability can be guaranteed tbr the LPF and PSF with considering the information delay, but the ranges of the control gains of the control laws are smaller than those without considering the information delay. For the MPF, the ＂weak＂ string stability, which can be guaranteed without considering the information delay, cannot be obtained with considering the information delay. The comparative simulations further demonstrate that the LPF shows better string stability, but the PSF shows better string scalable performance.展开更多
This paper proposes cooperative adaptive control schemes for a train platoon to improve efficient utility and guarantee string stability. The control schemes are developed based on a bidirectional strategy, i.e., the ...This paper proposes cooperative adaptive control schemes for a train platoon to improve efficient utility and guarantee string stability. The control schemes are developed based on a bidirectional strategy, i.e., the information of proximal（preceding and following） trains is used in the controller design. Based on available proximal information（prox-info） of location, speed, and acceleration, a direct adaptive control is designed to maintain the tracking interval at the minimum safe distance. Based on available prox-info of location, an observer-based adaptive control is designed to achieve the same target, which alleviates the requirements of equipped sensors to measure prox-info of speed and acceleration. The developed schemes are capable of on-line estimating of the unknown system parameters and stabilizing the closed-loop system, the string stability of train platoon is guaranteed on the basis of Lyapunov stability theorem. Numerical simulation results are presented to verify the effectiveness of the proposed control laws.展开更多
The class of bi-directional optimal velocity models can describe the bi-directional looking effect that usually exists in the reality and is even enhanced with the development of the connected vehicle technologies. It...The class of bi-directional optimal velocity models can describe the bi-directional looking effect that usually exists in the reality and is even enhanced with the development of the connected vehicle technologies. Its combined string stability condition can be obtained through the method of the ring-road based string stability analysis. However, the partial string stability about traffic fluctuation propagated backward or forward was neglected, which will be analyzed in detail in this work by the method of transfer function and its H∞ norm from the viewpoint of control theory. Then, through comparing the conditions of combined and partial string stabilities, their relationships can make traffic flow be divided into three distinguishable regions, displaying various combined and partial string stability performance. Finally, the numerical experiments verify the theoretical results and find that the final displaying string stability or instability performance results from the accumulated and offset effects of traffic fluctuations propagated from different directions.展开更多
The notion of string stability of a countably infinite interconnection of a class of nonlinear system was introduced. Intuitively, string stability implies uniform boundedness of all the stares of the interconnected s...The notion of string stability of a countably infinite interconnection of a class of nonlinear system was introduced. Intuitively, string stability implies uniform boundedness of all the stares of the interconnected system for all time if the initial states of the interconnected system are uniformly bounded. Vector V-function method used to judge the stability is generalized for infinite interconnected system and sufficient conditions which guarantee the asymptotic string stability of a class of interconnected system are given. The stability regions obtained here are much larger than those in previous papers. The method given here overcomes some difficulties to deal with stability of infinite nonlinear interconnected system in previous papers.展开更多
Leading cruise control(LCC)in mixed traffic has received wide attention as it can strengthen the capability of connected and automated vehicles in reducing traffic instability and smoothing mixed traffic.However,exist...Leading cruise control(LCC)in mixed traffic has received wide attention as it can strengthen the capability of connected and automated vehicles in reducing traffic instability and smoothing mixed traffic.However,existing predictive LCC cannot directly address head-to-tail string stability(HSS)since velocity fluctuation of human-driven vehicles behind cannot be handled by constraint design in MPC framework.To address this challenge,this paper proposes a control matching MPC approach for LCC in mixed traffic.A head-to-tail string stable feedback controller based on the inverse optimal velocity model is designed to guarantee HSS under bilateral topologies.Then,an MPC controller is proposed and the weighting matrices in the objective function are tuned to match the MPC controller with the head-to-tail string stable feedback controller.Straightforward analysis of HSS and physical/safety constraints satisfaction are neatly combined by the proposed control scheme.The feasibility and closed-loop stability of the MPC controller are analyzed.Finally,simulations verify the effectiveness of the proposed controller.展开更多
The Hamiltonian dynamics is adopted to solve the eigenvalue problem for transverse vibrations of axially moving strings. With the explicit Hamiltonian function the canonical equation of the free vibration is derived. ...The Hamiltonian dynamics is adopted to solve the eigenvalue problem for transverse vibrations of axially moving strings. With the explicit Hamiltonian function the canonical equation of the free vibration is derived. Non-singular modal functions are obtained through a linear, symplectic eigenvalue analysis, and the symplectic-type orthogonality conditions of modes are derived. Stability of the transverse motion is examined by means of analyzing the eigenvalues and their bifurcation, especially for strings transporting with the critical speed. It is pointed out that the motion of the string does not possess divergence instability at the critical speed due to the weak interaction between eigenvalue pairs. The expansion theorem is applied with the non-singular modal functions to solve the displacement response to free and forced vibrations. It is demonstrated that the modal functions can be used as the base functions for solving linear and nonlinear vibration problems.展开更多
For the constant distance spacing policy,the existing researches of the string stability focus on the single-predecessor information framework（SPIF） and predecessor-successor information framework（PSIF）.The resear...For the constant distance spacing policy,the existing researches of the string stability focus on the single-predecessor information framework（SPIF） and predecessor-successor information framework（PSIF）.The research results demonstrated that the string stability could not be guaranteed with the SPIF,and then the PSIF was proposed to resolve this string instability.But the issue,whether the string stability can be guaranteed when applying the PSIF,is still controversial.Meanwhile,most of the previous researches on the string stability were conducted without consideration of the parasitic time delays and lags.In this paper,the practical longitudinal vehicle dynamics model is built with consideration of the parasitic time delays and lags existing in the actuators,sensors or the communication systems.Secondly,the detailed theoretical analysis of string stability in frequency domain is conducted to demonstrate that the classical linear control laws can not ensure the string stability when applying both the symmetrical PSIF（SPSIF） and asymmetrical PSIF（APSIF）.Thirdly,a control law,which adds the position and velocity information of the leading vehicle,is proposed to guarantee string stability for small/medium platoon,and the other control law,which adds the acceleration information of the controlled vehicle,is proposed to guarantee string stability for large platoon as well as small/medium platoon.Finally,the comparative simulation is conducted to confirm the conducted analysis and the proposed control laws.The conducted research completes the means to analyze the string stability in frequency domain,provides the parameters＇ reference for the design and implementation of the practical automatic following controllers,and improves the reliability and stability of the platoon of automatic vehicles.展开更多
As a form of a future traffic system,a connected and automated vehicle(CAV)platoon is a typical nonlinear physical system.CAVs can communicate with each other and exchange information.However,communication failures ca...As a form of a future traffic system,a connected and automated vehicle(CAV)platoon is a typical nonlinear physical system.CAVs can communicate with each other and exchange information.However,communication failures can change the platoon system status.To characterize this change,a dynamic topology-based car-following model and its generalized form are proposed in this work.Then,a stability analysis method is explored.Finally,taking the dynamic cooperative intelligent driver model(DC-IDM)for example,a series of numerical simulations is conducted to analyze the platoon stability in different communication topology scenarios.The results show that the communication failures reduce the stability,but information from vehicles that are farther ahead and the use of a larger desired time headway can improve stability.Moreover,the critical ratio of communication failures required to ensure stability for different driving parameters is studied in this work.展开更多
This paper investigates a compound fault observer-based distributed prescribed-time faulttolerant control scheme of two-dimensional(2-D)connected vehicular platooning system(CvPS)subjected to multiple actuator faults ...This paper investigates a compound fault observer-based distributed prescribed-time faulttolerant control scheme of two-dimensional(2-D)connected vehicular platooning system(CvPS)subjected to multiple actuator faults and external disturbances.Firstly,the error dynamics of CvPS are designed to realise the multi-lane vehicle fusion,and vehicular platoon lane changing on the 2-D plane.Specifically,the longitudinal coupled spacing error dynamics are designed to guarantee the string stability performance.Then,to enhance the resilience performance and reduce the impact of the abrupt type,incipient type actuator faults,as well as disturbances,the improved compound fault observers are proposed to obtain the reconstruction of the compound fault information accurately within a prescribed time.Combine with the prescribed time control technology,the distributed fault-tolerant control scheme is designed to achieve the string stability,and the multi-dimensional internal stability,i.e.longitudinal stability,lateral stability and the heading angle tracking stability within a prescribed time.Finally,the comparison results also verify the effectiveness of the proposed scheme.展开更多
Wireless communication-enabled Cooperative Adaptive Cruise Control(CACC)is expected to improve the safety and traffic capacity of vehicle platoons.Existing CACC considers a conventional communication delay with fixed ...Wireless communication-enabled Cooperative Adaptive Cruise Control(CACC)is expected to improve the safety and traffic capacity of vehicle platoons.Existing CACC considers a conventional communication delay with fixed Vehicular Communication Network(VCN)topologies.However,when the network is under attack,the communication delay may be much higher,and the stability of the system may not be guaranteed.This paper proposes a novel communication Delay Aware CACC with Dynamic Network Topologies(DADNT).The main idea is that for various communication delays,in order to maximize the traffic capacity while guaranteeing stability and minimizing the following error,the CACC should dynamically adjust the VCN network topology to achieve the minimum inter-vehicle spacing.To this end,a multi-objective optimization problem is formulated,and a 3-step Divide-And-Conquer sub-optimal solution(3DAC)is proposed.Simulation results show that with 3DAC,the proposed DADNT with CACC can reduce the inter-vehicle spacing by 5%,10%,and 14%,respectively,compared with the traditional CACC with fixed one-vehicle,two-vehicle,and three-vehicle look-ahead network topologies,thereby improving the traffic efficiency.展开更多
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. This effect ...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. This effect is covered by the notion of string stability. 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. Using wireless inter-vehicle communications to provide real-time information of the preceding vehicle, in addition to the information obtained by common Adaptive Cruise Control （ACC） sensors, appears to significantly decrease the feasible time gap, which is shown by practical experiments with a test fleet consisting of six passenger vehicles. The large-scale deployment of this system, known as Cooperative ACC （CACC）, however, poses challenges with respect to the reliability of the wireless communication system. A solution for this scalability problem can be found in decreasing the transmission power and/or beaconing rate, or adapting the communications protocol. Although the main CACC objective is to increase road throughput, the first commercial application of CACC is foreseen to be in truck platooning, since short distance following is expected to yield significant fuel savings in this case.展开更多
As one of the typical applications of connected vehicles(CVs),the vehicle platoon control technique has been proven to have the advantages of reducing emissions,improving traffic throughout and driving safety.In this ...As one of the typical applications of connected vehicles(CVs),the vehicle platoon control technique has been proven to have the advantages of reducing emissions,improving traffic throughout and driving safety.In this paper,a unified hierarchical framework is designed for cooperative control of CVs with both heterogeneous model parameters and structures.By separating neighboring information interaction from local dynamics control,the proposed framework is designed to contain an upper-level observing layer and a lower-level tracking control layer,which helps address the heterogeneity in vehicle parameters and structures.Within the proposed framework,an observer is designed for following vehicles to observe the leading vehicle's states using neighboring communication,while a tracking controller is designed to track the observed leading vehicle using local feedback control.Closed-loop stability in the absence and presence of communication time delay is analyzed,and the observer is further extended to a finite time convergent one to address string stability under general communication topology.Numerical simulation and field experiment verify the effectiveness of the proposed method.展开更多
This study proposes two speed controllers based on a robust adaptive non-singular terminal sliding mode control approach for the cooperative adaptive cruise control problem in a connected and automated vehicular plato...This study proposes two speed controllers based on a robust adaptive non-singular terminal sliding mode control approach for the cooperative adaptive cruise control problem in a connected and automated vehicular platoon.The delay-based spacing policy is adopted to guarantee that all vehicles in the platoon track the same target velocity profile at the same position while maintaining a predefined time gap.Factors such as nonlinear vehicle longitudinal dynamics,engine dynamics with time delay,undulating road profiles,parameter uncertainties,and external disturbances are considered in the system modeling and controller design.Different control objectives are assigned to the leading and following vehicles.Then,controllers consisting of a sliding mode controller with parameter adaptive laws based on the ego vehicle’s state deviation and linear coupled state errors,and a Smith predictor for time delay compensation are designed.Both inner stability and strong string stability are guaranteed in the case of nonlinear sliding manifolds.Finally,the effectiveness of the proposed controllers and the benefits of 44.73%shorter stabilization time,11.20%less speed overshoot,and virtually zero steady-state inner vehicle distance deviation are illustrated in a simulation study of a seven-vehicle platoon cooperative adaptive cruise control and comparison experiments with a coupled sliding mode control approach.展开更多
A hierarchical control framework is applied for the distributed cooperative vehicular platoon using vehicular ad-hoc networks.The parameter-space-approach-based cooperative adaptive cruise control(CACC)controller is p...A hierarchical control framework is applied for the distributed cooperative vehicular platoon using vehicular ad-hoc networks.The parameter-space-approach-based cooperative adaptive cruise control(CACC)controller is proposed to guarantee the D-stability and the string stability considering the influence of the communication time delay and time lag of vehicular dynamic performance.This CACC controller combines the feedforward loop of the acceleration of the preceding vehicle with the feedback loop of the following errors,in which the gain of the feedforward loop is designed to decrease matching errors and the gains of the feedback loop are selected from the feasible region in the parameter space.To verify the effectiveness of the CACC controller,a six-vehicle platoon with a simplified vehicular dynamic is simulated under speed-up and stop scenarios.The simulation results demonstrate that the disturbance is attenuated along with the platoon and the following errors are convergent with well-designed convergent performance.A CarSim/Simulink co-simulation is designed to further verify the effectiveness of the hierarchical control framework and the rationality of the CACC controller in the real vehicular platoon application.The simulation results under the highway fuel economy test drive cycle show that the CACC controller improves the drive comfort and significantly decreases the following errors.展开更多
Cooperative and Adaptive Cruise Control(CACC)is widely focused to enhance driving fuel-efficiency by maintaining a close following gap.The ecology of CACC could be further enhanced by adapting to the rolling terrain.H...Cooperative and Adaptive Cruise Control(CACC)is widely focused to enhance driving fuel-efficiency by maintaining a close following gap.The ecology of CACC could be further enhanced by adapting to the rolling terrain.However,current studies cannot ensure both planning optimality and computational efficiency.Firstly,current studies are mostly formulated on the conventional time domain.These time domain based methods cannot ensure planning optimality for space-varying road slopes.Secondly,fuel consumption models are non-linear and hard to solve efficiently.Hence,this paper proposes a space domain based Ecological-CACC(Eco-CACC)controller.It is formulated into a nonlinear optimal control problem with the objective of optimizing global fuel consumptions.Furthermore,a differential dynamic programming-based solving method is developed to ensure real-time computational efficiency.Simulation results have shown that the proposed Eco-CACC controller can improve the average fuel saving by 37.67%at collector road and about 17.30%at major arterial.The string stability of the proposed method has been theoretically proven and experimentally validated.展开更多
This paper investigates the problem of fuel-efficient and safe control of autonomous vehicle platoons. We present a two-part hierarchical control method that can guarantee platoon stability with minimal fuel consumpti...This paper investigates the problem of fuel-efficient and safe control of autonomous vehicle platoons. We present a two-part hierarchical control method that can guarantee platoon stability with minimal fuel consumption. The first part vehicle controller is derived in the context of receding horizon optimal control by constructing and solving an optimization problem of overall fuel consumption. The Second part platoon controller is a complementation of the first part, which is given on the basis of platoon stability analysis. The effectiveness of the presented platoon control method is demonstrated by both numerical simulations and experiments with laboratory-scale Arduino cars.展开更多
基金Project(20070006011) supported by the Doctoral Foundation of Ministry of Education of China
文摘The effect of the information delay, which was caused by thc naturc of the distance sensors and wireless communication systems, on the string stability of platoon of automated vehicles was studied. The longitudinal vehicle dynamics model was built by taking the information delay into consideration, and three typical information frameworks, i.e., leader-predecessor framework （LPF）, multiple-predecessors framework （MPF） and predecessor-successor framework （PSF）, were defined and their related spacing error dynamics models in frequency domain were proposed. The string stability of platoon of automated vehicles was analyzed for the LPF, MPF and PSF, respectively. Meanwhile, the related sufficient string stable conditions were also obtained. The results demonstrate that the string stability can be guaranteed tbr the LPF and PSF with considering the information delay, but the ranges of the control gains of the control laws are smaller than those without considering the information delay. For the MPF, the ＂weak＂ string stability, which can be guaranteed without considering the information delay, cannot be obtained with considering the information delay. The comparative simulations further demonstrate that the LPF shows better string stability, but the PSF shows better string scalable performance.
基金Project supported by the Beijing Jiaotong University Research Program,China(Grant No.RCS2014ZT18)the Fundamental Research Funds for Central Universities,China(Grant No.2015JBZ007)the National Natural Science Foundation of China(Grant Nos.61233001,61322307,and 61304196)
文摘This paper proposes cooperative adaptive control schemes for a train platoon to improve efficient utility and guarantee string stability. The control schemes are developed based on a bidirectional strategy, i.e., the information of proximal（preceding and following） trains is used in the controller design. Based on available proximal information（prox-info） of location, speed, and acceleration, a direct adaptive control is designed to maintain the tracking interval at the minimum safe distance. Based on available prox-info of location, an observer-based adaptive control is designed to achieve the same target, which alleviates the requirements of equipped sensors to measure prox-info of speed and acceleration. The developed schemes are capable of on-line estimating of the unknown system parameters and stabilizing the closed-loop system, the string stability of train platoon is guaranteed on the basis of Lyapunov stability theorem. Numerical simulation results are presented to verify the effectiveness of the proposed control laws.
基金Projects(51108465,71371192)supported by the National Natural Science Foundation of ChinaProject(2014M552165)supported by China Postdoctoral Science FoundationProject(20113187851460)supported by Technology Project of the Ministry of Transport of China
文摘The class of bi-directional optimal velocity models can describe the bi-directional looking effect that usually exists in the reality and is even enhanced with the development of the connected vehicle technologies. Its combined string stability condition can be obtained through the method of the ring-road based string stability analysis. However, the partial string stability about traffic fluctuation propagated backward or forward was neglected, which will be analyzed in detail in this work by the method of transfer function and its H∞ norm from the viewpoint of control theory. Then, through comparing the conditions of combined and partial string stabilities, their relationships can make traffic flow be divided into three distinguishable regions, displaying various combined and partial string stability performance. Finally, the numerical experiments verify the theoretical results and find that the final displaying string stability or instability performance results from the accumulated and offset effects of traffic fluctuations propagated from different directions.
文摘The notion of string stability of a countably infinite interconnection of a class of nonlinear system was introduced. Intuitively, string stability implies uniform boundedness of all the stares of the interconnected system for all time if the initial states of the interconnected system are uniformly bounded. Vector V-function method used to judge the stability is generalized for infinite interconnected system and sufficient conditions which guarantee the asymptotic string stability of a class of interconnected system are given. The stability regions obtained here are much larger than those in previous papers. The method given here overcomes some difficulties to deal with stability of infinite nonlinear interconnected system in previous papers.
基金supported by National Natural Science Foundation of China(52222216,52372411)Young Elite Scientists Sponsorship Program by CAST(2022QNRC001)Hunan Provincial Natural Science Foundation of China(2023JJ10008).
文摘Leading cruise control(LCC)in mixed traffic has received wide attention as it can strengthen the capability of connected and automated vehicles in reducing traffic instability and smoothing mixed traffic.However,existing predictive LCC cannot directly address head-to-tail string stability(HSS)since velocity fluctuation of human-driven vehicles behind cannot be handled by constraint design in MPC framework.To address this challenge,this paper proposes a control matching MPC approach for LCC in mixed traffic.A head-to-tail string stable feedback controller based on the inverse optimal velocity model is designed to guarantee HSS under bilateral topologies.Then,an MPC controller is proposed and the weighting matrices in the objective function are tuned to match the MPC controller with the head-to-tail string stable feedback controller.Straightforward analysis of HSS and physical/safety constraints satisfaction are neatly combined by the proposed control scheme.The feasibility and closed-loop stability of the MPC controller are analyzed.Finally,simulations verify the effectiveness of the proposed controller.
基金supported by the National Natural Science Foundation of China(10472021,10421002 and 10032030)the NSFC-RFBR Collaboration Project(1031120166/10411120494)the Scientific Research Foundation for the Retumed 0verseas Chinese Scholars,State Education Ministry.
文摘The Hamiltonian dynamics is adopted to solve the eigenvalue problem for transverse vibrations of axially moving strings. With the explicit Hamiltonian function the canonical equation of the free vibration is derived. Non-singular modal functions are obtained through a linear, symplectic eigenvalue analysis, and the symplectic-type orthogonality conditions of modes are derived. Stability of the transverse motion is examined by means of analyzing the eigenvalues and their bifurcation, especially for strings transporting with the critical speed. It is pointed out that the motion of the string does not possess divergence instability at the critical speed due to the weak interaction between eigenvalue pairs. The expansion theorem is applied with the non-singular modal functions to solve the displacement response to free and forced vibrations. It is demonstrated that the modal functions can be used as the base functions for solving linear and nonlinear vibration problems.
基金supported by Doctoral Foundation of Ministry of Education of China (Grant No.20070006011)
文摘For the constant distance spacing policy,the existing researches of the string stability focus on the single-predecessor information framework（SPIF） and predecessor-successor information framework（PSIF）.The research results demonstrated that the string stability could not be guaranteed with the SPIF,and then the PSIF was proposed to resolve this string instability.But the issue,whether the string stability can be guaranteed when applying the PSIF,is still controversial.Meanwhile,most of the previous researches on the string stability were conducted without consideration of the parasitic time delays and lags.In this paper,the practical longitudinal vehicle dynamics model is built with consideration of the parasitic time delays and lags existing in the actuators,sensors or the communication systems.Secondly,the detailed theoretical analysis of string stability in frequency domain is conducted to demonstrate that the classical linear control laws can not ensure the string stability when applying both the symmetrical PSIF（SPSIF） and asymmetrical PSIF（APSIF）.Thirdly,a control law,which adds the position and velocity information of the leading vehicle,is proposed to guarantee string stability for small/medium platoon,and the other control law,which adds the acceleration information of the controlled vehicle,is proposed to guarantee string stability for large platoon as well as small/medium platoon.Finally,the comparative simulation is conducted to confirm the conducted analysis and the proposed control laws.The conducted research completes the means to analyze the string stability in frequency domain,provides the parameters＇ reference for the design and implementation of the practical automatic following controllers,and improves the reliability and stability of the platoon of automatic vehicles.
基金Project supported by the National Key Research and Development Project of China(Grant No.2018YFE0204300)the Beijing Municipal Science&Technology Commission(Grant No.Z211100004221008)the National Natural Science Foundation of China(Grant No.U1964206).
文摘As a form of a future traffic system,a connected and automated vehicle(CAV)platoon is a typical nonlinear physical system.CAVs can communicate with each other and exchange information.However,communication failures can change the platoon system status.To characterize this change,a dynamic topology-based car-following model and its generalized form are proposed in this work.Then,a stability analysis method is explored.Finally,taking the dynamic cooperative intelligent driver model(DC-IDM)for example,a series of numerical simulations is conducted to analyze the platoon stability in different communication topology scenarios.The results show that the communication failures reduce the stability,but information from vehicles that are farther ahead and the use of a larger desired time headway can improve stability.Moreover,the critical ratio of communication failures required to ensure stability for different driving parameters is studied in this work.
基金supported by the National Natural Science Foundation of China[grant number 62403106]the Postdoctoral Fellowship Program of CPSF[grant number GZC20240221]+2 种基金the Sichuan Science and Technology Program[grant number 2025ZNSFSC1520,2024NSFSC1491]the National Key Research and Development Plan Programs of China[grant number 2022YFE0120700]the Scientific and Technical Supporting Programs of Sichuan Province of China[grant number 2023YFG0200].
文摘This paper investigates a compound fault observer-based distributed prescribed-time faulttolerant control scheme of two-dimensional(2-D)connected vehicular platooning system(CvPS)subjected to multiple actuator faults and external disturbances.Firstly,the error dynamics of CvPS are designed to realise the multi-lane vehicle fusion,and vehicular platoon lane changing on the 2-D plane.Specifically,the longitudinal coupled spacing error dynamics are designed to guarantee the string stability performance.Then,to enhance the resilience performance and reduce the impact of the abrupt type,incipient type actuator faults,as well as disturbances,the improved compound fault observers are proposed to obtain the reconstruction of the compound fault information accurately within a prescribed time.Combine with the prescribed time control technology,the distributed fault-tolerant control scheme is designed to achieve the string stability,and the multi-dimensional internal stability,i.e.longitudinal stability,lateral stability and the heading angle tracking stability within a prescribed time.Finally,the comparison results also verify the effectiveness of the proposed scheme.
基金supported by the National Natural Science Foundation of China under Grant U21A20449in part by Jiangsu Provincial Key Research and Development Program under Grant BE2021013-2。
文摘Wireless communication-enabled Cooperative Adaptive Cruise Control(CACC)is expected to improve the safety and traffic capacity of vehicle platoons.Existing CACC considers a conventional communication delay with fixed Vehicular Communication Network(VCN)topologies.However,when the network is under attack,the communication delay may be much higher,and the stability of the system may not be guaranteed.This paper proposes a novel communication Delay Aware CACC with Dynamic Network Topologies(DADNT).The main idea is that for various communication delays,in order to maximize the traffic capacity while guaranteeing stability and minimizing the following error,the CACC should dynamically adjust the VCN network topology to achieve the minimum inter-vehicle spacing.To this end,a multi-objective optimization problem is formulated,and a 3-step Divide-And-Conquer sub-optimal solution(3DAC)is proposed.Simulation results show that with 3DAC,the proposed DADNT with CACC can reduce the inter-vehicle spacing by 5%,10%,and 14%,respectively,compared with the traditional CACC with fixed one-vehicle,two-vehicle,and three-vehicle look-ahead network topologies,thereby improving the traffic efficiency.
文摘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. This effect is covered by the notion of string stability. 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. Using wireless inter-vehicle communications to provide real-time information of the preceding vehicle, in addition to the information obtained by common Adaptive Cruise Control （ACC） sensors, appears to significantly decrease the feasible time gap, which is shown by practical experiments with a test fleet consisting of six passenger vehicles. The large-scale deployment of this system, known as Cooperative ACC （CACC）, however, poses challenges with respect to the reliability of the wireless communication system. A solution for this scalability problem can be found in decreasing the transmission power and/or beaconing rate, or adapting the communications protocol. Although the main CACC objective is to increase road throughput, the first commercial application of CACC is foreseen to be in truck platooning, since short distance following is expected to yield significant fuel savings in this case.
基金the National Key Research and Development Program of China(2021YFB2501803)the National Natural Science Foundation of China(52172384,52002126,52102394)+2 种基金Hunan Provincial Natural Science Foundation of China(2021JJ40065)the State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body(61775006)the Fundamental Research Funds for the Central Universities。
文摘As one of the typical applications of connected vehicles(CVs),the vehicle platoon control technique has been proven to have the advantages of reducing emissions,improving traffic throughout and driving safety.In this paper,a unified hierarchical framework is designed for cooperative control of CVs with both heterogeneous model parameters and structures.By separating neighboring information interaction from local dynamics control,the proposed framework is designed to contain an upper-level observing layer and a lower-level tracking control layer,which helps address the heterogeneity in vehicle parameters and structures.Within the proposed framework,an observer is designed for following vehicles to observe the leading vehicle's states using neighboring communication,while a tracking controller is designed to track the observed leading vehicle using local feedback control.Closed-loop stability in the absence and presence of communication time delay is analyzed,and the observer is further extended to a finite time convergent one to address string stability under general communication topology.Numerical simulation and field experiment verify the effectiveness of the proposed method.
基金the Research Project of CASCO Signal Ltd.(No.RE.Z0120032)。
文摘This study proposes two speed controllers based on a robust adaptive non-singular terminal sliding mode control approach for the cooperative adaptive cruise control problem in a connected and automated vehicular platoon.The delay-based spacing policy is adopted to guarantee that all vehicles in the platoon track the same target velocity profile at the same position while maintaining a predefined time gap.Factors such as nonlinear vehicle longitudinal dynamics,engine dynamics with time delay,undulating road profiles,parameter uncertainties,and external disturbances are considered in the system modeling and controller design.Different control objectives are assigned to the leading and following vehicles.Then,controllers consisting of a sliding mode controller with parameter adaptive laws based on the ego vehicle’s state deviation and linear coupled state errors,and a Smith predictor for time delay compensation are designed.Both inner stability and strong string stability are guaranteed in the case of nonlinear sliding manifolds.Finally,the effectiveness of the proposed controllers and the benefits of 44.73%shorter stabilization time,11.20%less speed overshoot,and virtually zero steady-state inner vehicle distance deviation are illustrated in a simulation study of a seven-vehicle platoon cooperative adaptive cruise control and comparison experiments with a coupled sliding mode control approach.
基金supported by the Jilin Province Key Technology and Development Program(No.20190302077GX)the National Key Technologies R&D Program of China during the 13th Five-Year Plan Period(No.2017YFC0601604).
文摘A hierarchical control framework is applied for the distributed cooperative vehicular platoon using vehicular ad-hoc networks.The parameter-space-approach-based cooperative adaptive cruise control(CACC)controller is proposed to guarantee the D-stability and the string stability considering the influence of the communication time delay and time lag of vehicular dynamic performance.This CACC controller combines the feedforward loop of the acceleration of the preceding vehicle with the feedback loop of the following errors,in which the gain of the feedforward loop is designed to decrease matching errors and the gains of the feedback loop are selected from the feasible region in the parameter space.To verify the effectiveness of the CACC controller,a six-vehicle platoon with a simplified vehicular dynamic is simulated under speed-up and stop scenarios.The simulation results demonstrate that the disturbance is attenuated along with the platoon and the following errors are convergent with well-designed convergent performance.A CarSim/Simulink co-simulation is designed to further verify the effectiveness of the hierarchical control framework and the rationality of the CACC controller in the real vehicular platoon application.The simulation results under the highway fuel economy test drive cycle show that the CACC controller improves the drive comfort and significantly decreases the following errors.
基金partially supported by National Key R&D Program of China(No.2022YFF0604905)National Natural Science Foundation of China(No.52302412 and 52372317)+5 种基金Shanghai Automotive Industry Science and Technology Development Foundation(No.2213)Tongji Zhongte Chair Professor Foundation(No.000000375-2018082)Shanghai Sailing Program(No.23YF1449600)Shanghai Post-doctoral Excellence Program(No.2022571)China Postdoctoral Science Foundation(No.2022M722405)Xiaomi Young Talents Program,and the Science Fund of State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle(No.32215011).
文摘Cooperative and Adaptive Cruise Control(CACC)is widely focused to enhance driving fuel-efficiency by maintaining a close following gap.The ecology of CACC could be further enhanced by adapting to the rolling terrain.However,current studies cannot ensure both planning optimality and computational efficiency.Firstly,current studies are mostly formulated on the conventional time domain.These time domain based methods cannot ensure planning optimality for space-varying road slopes.Secondly,fuel consumption models are non-linear and hard to solve efficiently.Hence,this paper proposes a space domain based Ecological-CACC(Eco-CACC)controller.It is formulated into a nonlinear optimal control problem with the objective of optimizing global fuel consumptions.Furthermore,a differential dynamic programming-based solving method is developed to ensure real-time computational efficiency.Simulation results have shown that the proposed Eco-CACC controller can improve the average fuel saving by 37.67%at collector road and about 17.30%at major arterial.The string stability of the proposed method has been theoretically proven and experimentally validated.
基金supported by the National Natural Science Foundation of China(Grant Nos.61273107 and 61573077)Dalian Leading Talent(Grant No.841252)
文摘This paper investigates the problem of fuel-efficient and safe control of autonomous vehicle platoons. We present a two-part hierarchical control method that can guarantee platoon stability with minimal fuel consumption. The first part vehicle controller is derived in the context of receding horizon optimal control by constructing and solving an optimization problem of overall fuel consumption. The Second part platoon controller is a complementation of the first part, which is given on the basis of platoon stability analysis. The effectiveness of the presented platoon control method is demonstrated by both numerical simulations and experiments with laboratory-scale Arduino cars.
