This study presents a general optimal trajectory planning(GOTP)framework for autonomous vehicles(AVs)that can effectively avoid obstacles and guide AVs to complete driving tasks safely and efficiently.Firstly,we emplo...This study presents a general optimal trajectory planning(GOTP)framework for autonomous vehicles(AVs)that can effectively avoid obstacles and guide AVs to complete driving tasks safely and efficiently.Firstly,we employ the fifth-order Bezier curve to generate and smooth the reference path along the road centerline.Cartesian coordinates are then transformed to achieve the curvature continuity of the generated curve.Considering the road constraints and vehicle dynamics,limited polynomial candidate trajectories are generated and smoothed in a curvilinear coordinate system.Furthermore,in selecting the optimal trajectory,we develop a unified and auto-tune objective function based on the principle of least action by employing AVs to simulate drivers’behavior and summarizing their manipulation characteristics of“seeking benefits and avoiding losses.”Finally,by integrating the idea of receding-horizon optimization,the proposed framework is achieved by considering dynamic multi-performance objectives and selecting trajectories that satisfy feasibility,optimality,and adaptability.Extensive simulations and experiments are performed,and the results demonstrate the framework’s feasibility and effectiveness,which avoids both dynamic and static obstacles and applies to various scenarios with multi-source interactive traffic participants.Moreover,we prove that the proposed method can guarantee real-time planning and safety requirements compared to drivers’manipulation.展开更多
The second law of thermodynamics implies that any animate and inanimate systems degrade and inevitably stops functioning.It is irreversible over time that can be labeled as‘‘the degradation arrow of time".From ...The second law of thermodynamics implies that any animate and inanimate systems degrade and inevitably stops functioning.It is irreversible over time that can be labeled as‘‘the degradation arrow of time".From perspective of products’reliability design,it is essential to build appropriate models of describing the degradation arrow of time.The current modeling approaches mainly include the model-driven(having assumed forms based on cognitive experience of mankind)and data-driven(using data learning techniques without form hypothesis)approaches.In this paper,we just investigate and review the model-driven degradation approaches,hoping to provide suggestions of the model construction or selection for scholars or engineers.First,for the single mechanism,degradation law models and stochastic process models are classified as separately depicting the tendency and fluctuation of degradation.For the degradation law model,we propose the concept of meta-models as original types for various personal models.For the stochastic process model,two main types including the non-monotonic and monotonical types are presented.Then,four multi-mechanism degradation types are discussed,that are competitive degradation,multi-stage degradation,coexistence of degradation and impact,and coexistence of degradation and failure.Besides,for the multi-performance degradation,independent and coupling models are introduced.The forms,connotations,applicability and insufficiency of these models are described with a series of examples from the literature and our own experiences.The final explicit suggestions about the potential future work are provided for the development of new degradation models.展开更多
基金supported by the National Natural Science Foundation of China(the Key Project,52131201Science Fund for Creative Research Groups,52221005)+1 种基金the China Scholarship Councilthe Joint Laboratory for Internet of Vehicles,Ministry of Education–China MOBILE Communications Corporation。
文摘This study presents a general optimal trajectory planning(GOTP)framework for autonomous vehicles(AVs)that can effectively avoid obstacles and guide AVs to complete driving tasks safely and efficiently.Firstly,we employ the fifth-order Bezier curve to generate and smooth the reference path along the road centerline.Cartesian coordinates are then transformed to achieve the curvature continuity of the generated curve.Considering the road constraints and vehicle dynamics,limited polynomial candidate trajectories are generated and smoothed in a curvilinear coordinate system.Furthermore,in selecting the optimal trajectory,we develop a unified and auto-tune objective function based on the principle of least action by employing AVs to simulate drivers’behavior and summarizing their manipulation characteristics of“seeking benefits and avoiding losses.”Finally,by integrating the idea of receding-horizon optimization,the proposed framework is achieved by considering dynamic multi-performance objectives and selecting trajectories that satisfy feasibility,optimality,and adaptability.Extensive simulations and experiments are performed,and the results demonstrate the framework’s feasibility and effectiveness,which avoids both dynamic and static obstacles and applies to various scenarios with multi-source interactive traffic participants.Moreover,we prove that the proposed method can guarantee real-time planning and safety requirements compared to drivers’manipulation.
基金co-supported by the National Natural Science Foundation of China(Nos.51675025,and 61573043)。
文摘The second law of thermodynamics implies that any animate and inanimate systems degrade and inevitably stops functioning.It is irreversible over time that can be labeled as‘‘the degradation arrow of time".From perspective of products’reliability design,it is essential to build appropriate models of describing the degradation arrow of time.The current modeling approaches mainly include the model-driven(having assumed forms based on cognitive experience of mankind)and data-driven(using data learning techniques without form hypothesis)approaches.In this paper,we just investigate and review the model-driven degradation approaches,hoping to provide suggestions of the model construction or selection for scholars or engineers.First,for the single mechanism,degradation law models and stochastic process models are classified as separately depicting the tendency and fluctuation of degradation.For the degradation law model,we propose the concept of meta-models as original types for various personal models.For the stochastic process model,two main types including the non-monotonic and monotonical types are presented.Then,four multi-mechanism degradation types are discussed,that are competitive degradation,multi-stage degradation,coexistence of degradation and impact,and coexistence of degradation and failure.Besides,for the multi-performance degradation,independent and coupling models are introduced.The forms,connotations,applicability and insufficiency of these models are described with a series of examples from the literature and our own experiences.The final explicit suggestions about the potential future work are provided for the development of new degradation models.
