Wheeled mobile robot is one of the well-known nonholonomic systems. A two-wheeled sell-balance robot is taken as the research objective. This paper carried out a detailed force analysis of the robot and established a ...Wheeled mobile robot is one of the well-known nonholonomic systems. A two-wheeled sell-balance robot is taken as the research objective. This paper carried out a detailed force analysis of the robot and established a non-linear dynamics model. An adaptive tracking controller for the kinematic model of a nonhotonomic mobile robot with unknown parameters is also proposed. Using control Lyapunov function （CLF）, the controller＇s global asymptotic stability has been proven. The adaptive trajectory tracking controller decreases the disturbance in the course of tracking control and enhances the real-time control characteristics. The simulation result indicated that the wheeled mobile robot tracking can be effectively controlled.展开更多
Many covariate-adaptive randomization procedures have been proposed and implemented to balance important covariates in clinical trials. These methods are usually based on fully observed covariates. In practice,the cov...Many covariate-adaptive randomization procedures have been proposed and implemented to balance important covariates in clinical trials. These methods are usually based on fully observed covariates. In practice,the covariates of a patient are often partially missing. We propose a novel covariate-adaptive design to deal with missing covariates and study its properties. For the proposed design, we show that as the number of patients increases, the overall imbalance, observed margin imbalance and fully observed stratum imbalance are bounded in probability. Under certain covariate-dependent missing mechanism, the proposed design can balance missing covariates as if the covariates are observed. Finally, we explore our methods and theoretical findings through simulations.展开更多
基金Supported by the National High Technology Research and Development Programme of China (No. 2006AA04Z245)the Program for Changjiang Scholars and Innovative Research Team in University ( No. IRT0423)the Fund for Foreign Scholars in University Research and Teaching Programs (No. B07018)
文摘Wheeled mobile robot is one of the well-known nonholonomic systems. A two-wheeled sell-balance robot is taken as the research objective. This paper carried out a detailed force analysis of the robot and established a non-linear dynamics model. An adaptive tracking controller for the kinematic model of a nonhotonomic mobile robot with unknown parameters is also proposed. Using control Lyapunov function （CLF）, the controller＇s global asymptotic stability has been proven. The adaptive trajectory tracking controller decreases the disturbance in the course of tracking control and enhances the real-time control characteristics. The simulation result indicated that the wheeled mobile robot tracking can be effectively controlled.
基金supported by National Natural Science Foundation of China(Grant Nos.11371366 and 11201479)Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120004120007)the Basic Research Funds in Renmin University of China from the central government(Grant Nos.13XNLJ03 and 12XNQ049)
文摘Many covariate-adaptive randomization procedures have been proposed and implemented to balance important covariates in clinical trials. These methods are usually based on fully observed covariates. In practice,the covariates of a patient are often partially missing. We propose a novel covariate-adaptive design to deal with missing covariates and study its properties. For the proposed design, we show that as the number of patients increases, the overall imbalance, observed margin imbalance and fully observed stratum imbalance are bounded in probability. Under certain covariate-dependent missing mechanism, the proposed design can balance missing covariates as if the covariates are observed. Finally, we explore our methods and theoretical findings through simulations.
