This paper presents the design of a robust control system for a high-purity distillation column. It is concerned with the design of a two degree-of-freedom (2DOF) product-composition controller for a high-purity disti...This paper presents the design of a robust control system for a high-purity distillation column. It is concerned with the design of a two degree-of-freedom (2DOF) product-composition controller for a high-purity distillation column. The H<sub>∞</sub> optimization problem is set up to ensure a guaranteed level of robust stability, robust disturbance attenuation and robust reference tracking performance.展开更多
A novel time-domain identification technique is developed for the seismic response analysis of soil-structure interaction.A two-degree-of-freedom (2DOF) model with eight lumped parameters is adopted to model the frequ...A novel time-domain identification technique is developed for the seismic response analysis of soil-structure interaction.A two-degree-of-freedom (2DOF) model with eight lumped parameters is adopted to model the frequency- dependent behavior of soils.For layered soil,the equivalent eight parameters of the 2DOF model are identified by the extended Kalman filter (EKF) method using recorded seismic data.The polynomial approximations for derivation of state estimators are applied in the EKF procedure.A realistic identification example is given for the layered-soil of a building site in Anchorage,Alaska in the United States.Results of the example demonstrate the feasibility and practicality of the proposed identification technique.The 2DOF soil model and the identification technique can be used for nonlinear response analysis of soil-structure interaction in the time-domain for layered or complex soil conditions.The identified parameters can be stored in a database tor use in other similar soil conditions,lfa universal database that covers information related to most soil conditions is developed in the thture,engineers could conveniently perform time history analyses of soil-structural interaction.展开更多
Current research on spherical parallel mechanisms(SPMs)mainly focus on surgical robots,exoskeleton robots,entertainment equipment,and other fields.However,compared with the SPM,the structure types and research content...Current research on spherical parallel mechanisms(SPMs)mainly focus on surgical robots,exoskeleton robots,entertainment equipment,and other fields.However,compared with the SPM,the structure types and research contents of the SPM are not abundant enough.In this paper,a novel two-degree-of-freedom(2DOF)SPM with symmetrical structure is proposed and analyzed.First,the models of forward kinematics and inverse kinematics are established based on D-H parameters,and the Jacobian matrix of the mechanism is obtained and verified.Second,the workspace of the mechanism is obtained according to inverse kinematics and link interference conditions.Next,rotational characteristics analysis shows that the end effector can achieve continuous rotation about an axis located in the mid-plane and passing through the rotation center of the mechanism.Moreover,the rotational characteristics of the mechanism are proved,and motion planning is carried out.A numerical example is given to verify the kinematics analysis and motion planning.Finally,some variant mechanisms can be synthesized.This work lays the foundation for the motion control and practical application of this 2DOF SPM.展开更多
文摘This paper presents the design of a robust control system for a high-purity distillation column. It is concerned with the design of a two degree-of-freedom (2DOF) product-composition controller for a high-purity distillation column. The H<sub>∞</sub> optimization problem is set up to ensure a guaranteed level of robust stability, robust disturbance attenuation and robust reference tracking performance.
文摘A novel time-domain identification technique is developed for the seismic response analysis of soil-structure interaction.A two-degree-of-freedom (2DOF) model with eight lumped parameters is adopted to model the frequency- dependent behavior of soils.For layered soil,the equivalent eight parameters of the 2DOF model are identified by the extended Kalman filter (EKF) method using recorded seismic data.The polynomial approximations for derivation of state estimators are applied in the EKF procedure.A realistic identification example is given for the layered-soil of a building site in Anchorage,Alaska in the United States.Results of the example demonstrate the feasibility and practicality of the proposed identification technique.The 2DOF soil model and the identification technique can be used for nonlinear response analysis of soil-structure interaction in the time-domain for layered or complex soil conditions.The identified parameters can be stored in a database tor use in other similar soil conditions,lfa universal database that covers information related to most soil conditions is developed in the thture,engineers could conveniently perform time history analyses of soil-structural interaction.
基金Supported by National Natural Science Foundation of China(Grant No.51775474)。
文摘Current research on spherical parallel mechanisms(SPMs)mainly focus on surgical robots,exoskeleton robots,entertainment equipment,and other fields.However,compared with the SPM,the structure types and research contents of the SPM are not abundant enough.In this paper,a novel two-degree-of-freedom(2DOF)SPM with symmetrical structure is proposed and analyzed.First,the models of forward kinematics and inverse kinematics are established based on D-H parameters,and the Jacobian matrix of the mechanism is obtained and verified.Second,the workspace of the mechanism is obtained according to inverse kinematics and link interference conditions.Next,rotational characteristics analysis shows that the end effector can achieve continuous rotation about an axis located in the mid-plane and passing through the rotation center of the mechanism.Moreover,the rotational characteristics of the mechanism are proved,and motion planning is carried out.A numerical example is given to verify the kinematics analysis and motion planning.Finally,some variant mechanisms can be synthesized.This work lays the foundation for the motion control and practical application of this 2DOF SPM.
