Due to errors in vehicle dynamics modeling,uncertainty in model parameters,and disturbances from curvature,the performance of the path tracking controller is poor or even unstable under high-speed and large-curvature ...Due to errors in vehicle dynamics modeling,uncertainty in model parameters,and disturbances from curvature,the performance of the path tracking controller is poor or even unstable under high-speed and large-curvature conditions.Therefore,a path tracking robust control strategy based on force-driven H_(∞)and MPC is proposed.To fully exploit the nonlinear dynamics characteristics of tires,a force-driven state space model of a path tracking system based on a linear time-varying tire model is established;the H_(∞)and MPC methods are used to design a robust controller.Considering disturbance and system state constraints,the robust control constraint model based on LMI is established.Finally,the proposed controller is validated through joint simulations using CarSim and MATLAB.The results show that the maximum lateral deviation is reduced by 17.07%,and the maximum course angle deviation is reduced by 13.04%under large curvature disturbance conditions.The maximum lateral deviation is reduced by 27.85%,and the maximum course angle deviation is reduced by 31.17%under conditions of uncertain road adhesion coefficients.Based on the controller’s performance,the proposed controller effectively mitigates modeling errors,parameter uncertainties,and curvature disturbances.展开更多
Traditional two-dimensional(2D)cell cultures lack the extracellular matrix(ECM)-like structure or dynamic fluidic microenvironment for cells to maintain in vivo functionality.Three-dimensional(3D)tissue scaffolds,on t...Traditional two-dimensional(2D)cell cultures lack the extracellular matrix(ECM)-like structure or dynamic fluidic microenvironment for cells to maintain in vivo functionality.Three-dimensional(3D)tissue scaffolds,on the other hand,could provide the ECM-like microenvironment for cells to reformulate into tissue or organoids that are highly useful for in vitro drug screening.In this study,a high-throughput two-chamber 3D microscale tissue model platform is developed.Porous scaffolds are selectively foamed on a commercially available compact disk using laser.Perfusion of cell culture medium is achieved with centrifugal force-driven diffusion by disk rotation.Experimental studies were conducted on the fabrication process under various gas saturation and laser power conditions.Cell cultures were performed with two types of human cell lines:M059K and C3A-sub28.It is shown that the structure of microscale porous scaffolds can be controlled with laser foaming parameters and that coating with polydopamine these scaffolds are inducive for cell attachment and aggregation,forming a 3D network.With many such two-chamber models fabricated on a single CD and perfusion driven by the centrifugal force from rotation,the proposed platform provides a simple solution to the high-cost and lengthy drug development process with a high-throughput and physiologically more relevant tissue model system.展开更多
In cabin-type component alignment, digital measurement technology is usually adopted to provide guidance for assembly. Depending on the system of measurement, the alignment process can be divided into measurement-assi...In cabin-type component alignment, digital measurement technology is usually adopted to provide guidance for assembly. Depending on the system of measurement, the alignment process can be divided into measurement-assisted assembly(MAA) and force-driven assembly. In MAA,relative pose between components is directly measured to guide assembly, while in force-driven assembly, only contact state can be recognized according to measured six-dimensional force and torque(6 D F/T) and the process is completed based on preset assembly strategy. Aiming to improve the efficiency of force-driven cabin-type component alignment, this paper proposed a heuristic alignment method based on multi-source data fusion. In this method, measured 6 D F/T, pose data and geometric information of components are fused to calculate the relative pose between components and guide the movement of pose adjustment platform. Among these data types, pose data and measured 6 D F/T are combined as data set. To collect the data sets needed for data fusion, dynamic gravity compensation method and hybrid motion control method are designed. Then the relative pose calculation method is elaborated, which transforms collected data sets into discrete geometric elements and calculates the relative poses based on the geometric information of components.Finally, experiments are conducted in simulation environment and the results show that the proposed alignment method is feasible and effective.展开更多
基金Supported by Qinghai University Youth Research Fund,China(Grant No.2023-QGY-15)。
文摘Due to errors in vehicle dynamics modeling,uncertainty in model parameters,and disturbances from curvature,the performance of the path tracking controller is poor or even unstable under high-speed and large-curvature conditions.Therefore,a path tracking robust control strategy based on force-driven H_(∞)and MPC is proposed.To fully exploit the nonlinear dynamics characteristics of tires,a force-driven state space model of a path tracking system based on a linear time-varying tire model is established;the H_(∞)and MPC methods are used to design a robust controller.Considering disturbance and system state constraints,the robust control constraint model based on LMI is established.Finally,the proposed controller is validated through joint simulations using CarSim and MATLAB.The results show that the maximum lateral deviation is reduced by 17.07%,and the maximum course angle deviation is reduced by 13.04%under large curvature disturbance conditions.The maximum lateral deviation is reduced by 27.85%,and the maximum course angle deviation is reduced by 31.17%under conditions of uncertain road adhesion coefficients.Based on the controller’s performance,the proposed controller effectively mitigates modeling errors,parameter uncertainties,and curvature disturbances.
基金supported by the US National Science Foundation under Grant No.CMMI-1131710.
文摘Traditional two-dimensional(2D)cell cultures lack the extracellular matrix(ECM)-like structure or dynamic fluidic microenvironment for cells to maintain in vivo functionality.Three-dimensional(3D)tissue scaffolds,on the other hand,could provide the ECM-like microenvironment for cells to reformulate into tissue or organoids that are highly useful for in vitro drug screening.In this study,a high-throughput two-chamber 3D microscale tissue model platform is developed.Porous scaffolds are selectively foamed on a commercially available compact disk using laser.Perfusion of cell culture medium is achieved with centrifugal force-driven diffusion by disk rotation.Experimental studies were conducted on the fabrication process under various gas saturation and laser power conditions.Cell cultures were performed with two types of human cell lines:M059K and C3A-sub28.It is shown that the structure of microscale porous scaffolds can be controlled with laser foaming parameters and that coating with polydopamine these scaffolds are inducive for cell attachment and aggregation,forming a 3D network.With many such two-chamber models fabricated on a single CD and perfusion driven by the centrifugal force from rotation,the proposed platform provides a simple solution to the high-cost and lengthy drug development process with a high-throughput and physiologically more relevant tissue model system.
基金co-supported by the Special Research on Civil Aircraft of China (No.MJZ-2017-J-96)the Defense Industrial Technology Development Program of China (No.JCKY2016206B009)。
文摘In cabin-type component alignment, digital measurement technology is usually adopted to provide guidance for assembly. Depending on the system of measurement, the alignment process can be divided into measurement-assisted assembly(MAA) and force-driven assembly. In MAA,relative pose between components is directly measured to guide assembly, while in force-driven assembly, only contact state can be recognized according to measured six-dimensional force and torque(6 D F/T) and the process is completed based on preset assembly strategy. Aiming to improve the efficiency of force-driven cabin-type component alignment, this paper proposed a heuristic alignment method based on multi-source data fusion. In this method, measured 6 D F/T, pose data and geometric information of components are fused to calculate the relative pose between components and guide the movement of pose adjustment platform. Among these data types, pose data and measured 6 D F/T are combined as data set. To collect the data sets needed for data fusion, dynamic gravity compensation method and hybrid motion control method are designed. Then the relative pose calculation method is elaborated, which transforms collected data sets into discrete geometric elements and calculates the relative poses based on the geometric information of components.Finally, experiments are conducted in simulation environment and the results show that the proposed alignment method is feasible and effective.
