In this study, we present a framework based on a prediction model that facilitates user access to a number of services in a smart living environment. Users must be able to access all available services continuously eq...In this study, we present a framework based on a prediction model that facilitates user access to a number of services in a smart living environment. Users must be able to access all available services continuously equipped with mobile devices or smart objects without being impacted by technical constraints such as performance or memory issues, regardless of their physical location and mobility. To achieve this goal, we propose the use of cloudlet-based architecture that serves as distributed cloud resources with specific ranges of influence and a realtime processing framework that tracks events and preferences of the end consumers, predicts their requirements,and recommends services to optimize resource utilization and service response time.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
Aiming at the tele-operation instability caused by time delay of internet information transfer for internet based tele-robotics, this paper proposes a novel control framework for internet based tele-robotics, which ca...Aiming at the tele-operation instability caused by time delay of internet information transfer for internet based tele-robotics, this paper proposes a novel control framework for internet based tele-robotics, which can guarantee the non-distortion-transfer of control information and reduce the difference of action time between the local simulated virtual robot and the remote real robot. This framework is insensitive to the inherent internet time delay, and differs from other tele-robotics systems that try to use some mathematic models to describe the internet delay or take some assumptions. In order to verify the framework, a 4-DOF fischertechnik industry robot tele-operation system has been developed using the new proposed framework. Experimental results demonstrate the applicable performance of the new framework. The framework is open structured and can be applied to other general purposed tele-operation systems.展开更多
基金Financial support for this work,provided by the National Natural Science Foundation of China(No.60974126)the Natural Science Foundation of Jiangsu Province(No.BK2009094)
基金supported by the National Institute of Standards and Technologies(NIST)
文摘In this study, we present a framework based on a prediction model that facilitates user access to a number of services in a smart living environment. Users must be able to access all available services continuously equipped with mobile devices or smart objects without being impacted by technical constraints such as performance or memory issues, regardless of their physical location and mobility. To achieve this goal, we propose the use of cloudlet-based architecture that serves as distributed cloud resources with specific ranges of influence and a realtime processing framework that tracks events and preferences of the end consumers, predicts their requirements,and recommends services to optimize resource utilization and service response time.
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Sponsored by the National Natural Science Foundation of China (Grant No. 60776816)Scientific Research Foundation of Education Department of Yunnan Province (Grant No.08Y10326)
文摘Aiming at the tele-operation instability caused by time delay of internet information transfer for internet based tele-robotics, this paper proposes a novel control framework for internet based tele-robotics, which can guarantee the non-distortion-transfer of control information and reduce the difference of action time between the local simulated virtual robot and the remote real robot. This framework is insensitive to the inherent internet time delay, and differs from other tele-robotics systems that try to use some mathematic models to describe the internet delay or take some assumptions. In order to verify the framework, a 4-DOF fischertechnik industry robot tele-operation system has been developed using the new proposed framework. Experimental results demonstrate the applicable performance of the new framework. The framework is open structured and can be applied to other general purposed tele-operation systems.
