This paper presents a systematic methodology for analyzing and optimizing an innovative antenna mount designed for phased array antennas, implemented through a novel 2-PSS&1-RR circular-rail parallel mechanism. In...This paper presents a systematic methodology for analyzing and optimizing an innovative antenna mount designed for phased array antennas, implemented through a novel 2-PSS&1-RR circular-rail parallel mechanism. Initially, a comparative motion analysis between the 3D model of the mount and its full-scale prototype is conducted to validate effectiveness. Given the inherent complexity, a kinematic mapping model is established between the mount and the crank-slider linkage, providing a guiding framework for subsequent analysis and optimization. Guided by this model, feasible inverse and forward solutions are derived, enabling precise identification of stiffness singularities. The concept of singularity distance is thus introduced to reflect the structural stiffness of the mount. Subsequently, also guided by the mapping model, a heuristic algorithm incorporating two backtracking procedures is developed to reduce the mount's mass. Additionally, a parametric finite-element model is employed to explore the relation between singularity distance and structural stiffness. The results indicate a significant reduction(about 16%) in the antenna mount's mass through the developed algorithm, while highlighting the singularity distance as an effective stiffness indicator for this type of antenna mount.展开更多
A method of 3 D kinematics simulation of robot fighting platform （RFP） in virtual environment is proposed with the aim of enhancing vision telepresence. Based on the theory of space coordinate transformation, kinema...A method of 3 D kinematics simulation of robot fighting platform （RFP） in virtual environment is proposed with the aim of enhancing vision telepresence. Based on the theory of space coordinate transformation, kinematics equat!ons of RFP are formulated; followed by applying a method of modeling using 3DMAX software to build an RFP＇s 3D geometric model before a 3D kinematics simulation system of RFP is completed based on virtual reality technology and Open Inventor VC ＋ ＋. Test results have indicated that this system can perform RFP＇s kinematics simulation in virtual environment. It can also imitate RFP＇s motion states and environmental features well. Moreover, not only can better real-time performances and interactions be achieved but also operator＇s vision telepresence be enhanced, therefore this approach may help lay the foundation for the realization of RFP＇s teleoperation with vision telepresence.展开更多
Accurate modeling and simulation of autonomous underwater vehicle （AUV） is essential for autonomous control and maneuverability research. In this paper, a mini AUV- ＂MAUV-Ⅱ＂ was researched and the nonlinear mathe...Accurate modeling and simulation of autonomous underwater vehicle （AUV） is essential for autonomous control and maneuverability research. In this paper, a mini AUV- ＂MAUV-Ⅱ＂ was researched and the nonlinear mathematic model of the AUV in spatial motion was derived based on momentum theorem. The forces acting on AUV were resolved to several modules which were expressed in matrix form. Based on the motion model and combined with virtual reality technology, a motion simulation system was constructed. Considering the characteristic of ＂MAUV-Ⅱ ＂, the heading control and depth control were simulated by adopting S-surface control method. A long distance traveling simulation experiment based on target planning was also done. The simulation results show that the ＂MAUV-Ⅱ＂ has good spatial maneuverability, and verify the feasibility and reliability of control software.展开更多
A new parameter identification method is proposed to solve the slippage problem when tracked mobile robots execute turning motions.Such motion is divided into two states in this paper:pivot turning and coupled turning...A new parameter identification method is proposed to solve the slippage problem when tracked mobile robots execute turning motions.Such motion is divided into two states in this paper:pivot turning and coupled turning between angular velocity and linear velocity.In the processing of pivot turning,the slippage parameters could be obtained by measuring the end point in a square path.In the process of coupled turning,the slippage parameters could be calculated by measuring the perimeter of a circular path and the linear distance between the start and end points.The identification results showed that slippage parameters were affected by velocity.Therefore,a fuzzy rule base was established with the basis on the identification data,and a fuzzy controller was applied to motion control and dead reckoning.This method effectively compensated for errors resulting in unequal tension between the left and right tracks,structural dimensions and slippage.The results demonstrated that the accuracy of robot positioning and control could be substantially improved on a rigid floor.展开更多
At present,the cranes used at sea have several shortcomings in terms of flexibility,efficiency,and safety.Therefore,a floating multi-robot coordinated lifting system is proposed to fulfill the offshore lifting require...At present,the cranes used at sea have several shortcomings in terms of flexibility,efficiency,and safety.Therefore,a floating multi-robot coordinated lifting system is proposed to fulfill the offshore lifting requirements.First,the structure of the lifting system is established according to the lifting task,the kinematic model of the system is developed by using the D–H coordinate transformation,and the dynamic model is developed based on rigid-body dynamics and hydrodynamics.Then,the static and dynamic workspace of the lifting system are analyzed,and the solving steps of the workspace are given by using the Monte–Carlo method.The effect of the load mass and the maximum allowable tension of the cable on the workspace is examined by simulation.Results show that the lifting system has limited carrying capacity and a data reference for selecting the structural parameters by analyzing the factors affecting the workspace.Findings provide a basis for further research on the optimal design of structural parameters and the determination of safe configurations of the lifting system.展开更多
Experimental and theoretical studies of drag embedment plate anchors recently carried out in Tianjin University are summarized in this research paper, which involve a series of important topics relevant to the study o...Experimental and theoretical studies of drag embedment plate anchors recently carried out in Tianjin University are summarized in this research paper, which involve a series of important topics relevant to the study of drag anchors. The techniques for measuring the trajectory and movement direction of drag anchors in soils, the techniques for measuring the moving embedment point and reverse eatenary shape of the embedded drag line, the penetration mechanism and kinematic behavior of drag anchors, the ultimate embedment depth of drag anchors, the movement direction of the anchor with an arbitrary fluke section, the reverse catenary properties of the embedded drag line, the interaetional properties between drag anchor and installation line, the kinematic model of drag anchors in seabed soils, and the analytical method for predicting the anchor trajectory in soils will all be examined. The present work remarkably reduces the uncertainties in design and analysis of drag embedment plate anchors, and is beneficial to improving the application of this new type of drag anchor in offshore engineering.展开更多
基金financed by the National Key Research and Development Program of China,High efficiency space satellite charging system based on microwave wireless energy transfer technology(Grant No.2021YFB3900304)。
文摘This paper presents a systematic methodology for analyzing and optimizing an innovative antenna mount designed for phased array antennas, implemented through a novel 2-PSS&1-RR circular-rail parallel mechanism. Initially, a comparative motion analysis between the 3D model of the mount and its full-scale prototype is conducted to validate effectiveness. Given the inherent complexity, a kinematic mapping model is established between the mount and the crank-slider linkage, providing a guiding framework for subsequent analysis and optimization. Guided by this model, feasible inverse and forward solutions are derived, enabling precise identification of stiffness singularities. The concept of singularity distance is thus introduced to reflect the structural stiffness of the mount. Subsequently, also guided by the mapping model, a heuristic algorithm incorporating two backtracking procedures is developed to reduce the mount's mass. Additionally, a parametric finite-element model is employed to explore the relation between singularity distance and structural stiffness. The results indicate a significant reduction(about 16%) in the antenna mount's mass through the developed algorithm, while highlighting the singularity distance as an effective stiffness indicator for this type of antenna mount.
基金Sponsored by Independent Research Projects of State Key Laboratory (ZDKT08-05)
文摘A method of 3 D kinematics simulation of robot fighting platform （RFP） in virtual environment is proposed with the aim of enhancing vision telepresence. Based on the theory of space coordinate transformation, kinematics equat!ons of RFP are formulated; followed by applying a method of modeling using 3DMAX software to build an RFP＇s 3D geometric model before a 3D kinematics simulation system of RFP is completed based on virtual reality technology and Open Inventor VC ＋ ＋. Test results have indicated that this system can perform RFP＇s kinematics simulation in virtual environment. It can also imitate RFP＇s motion states and environmental features well. Moreover, not only can better real-time performances and interactions be achieved but also operator＇s vision telepresence be enhanced, therefore this approach may help lay the foundation for the realization of RFP＇s teleoperation with vision telepresence.
基金Supported by National Natural Science Foundation under Grant No.50879014
文摘Accurate modeling and simulation of autonomous underwater vehicle （AUV） is essential for autonomous control and maneuverability research. In this paper, a mini AUV- ＂MAUV-Ⅱ＂ was researched and the nonlinear mathematic model of the AUV in spatial motion was derived based on momentum theorem. The forces acting on AUV were resolved to several modules which were expressed in matrix form. Based on the motion model and combined with virtual reality technology, a motion simulation system was constructed. Considering the characteristic of ＂MAUV-Ⅱ ＂, the heading control and depth control were simulated by adopting S-surface control method. A long distance traveling simulation experiment based on target planning was also done. The simulation results show that the ＂MAUV-Ⅱ＂ has good spatial maneuverability, and verify the feasibility and reliability of control software.
文摘A new parameter identification method is proposed to solve the slippage problem when tracked mobile robots execute turning motions.Such motion is divided into two states in this paper:pivot turning and coupled turning between angular velocity and linear velocity.In the processing of pivot turning,the slippage parameters could be obtained by measuring the end point in a square path.In the process of coupled turning,the slippage parameters could be calculated by measuring the perimeter of a circular path and the linear distance between the start and end points.The identification results showed that slippage parameters were affected by velocity.Therefore,a fuzzy rule base was established with the basis on the identification data,and a fuzzy controller was applied to motion control and dead reckoning.This method effectively compensated for errors resulting in unequal tension between the left and right tracks,structural dimensions and slippage.The results demonstrated that the accuracy of robot positioning and control could be substantially improved on a rigid floor.
基金Supported by the National Natural Science Foundation of China under Grant No.51965032the National Natural Science Foundation of Gansu Province of China under Grant No.22JR5RA319+1 种基金the Science and Technology Foundation of Gansu Province of China under Grant No.21YF5WA060the Excellent Doctoral Student Foundation of Gansu Province of China under Grant No.23JRRA842。
文摘At present,the cranes used at sea have several shortcomings in terms of flexibility,efficiency,and safety.Therefore,a floating multi-robot coordinated lifting system is proposed to fulfill the offshore lifting requirements.First,the structure of the lifting system is established according to the lifting task,the kinematic model of the system is developed by using the D–H coordinate transformation,and the dynamic model is developed based on rigid-body dynamics and hydrodynamics.Then,the static and dynamic workspace of the lifting system are analyzed,and the solving steps of the workspace are given by using the Monte–Carlo method.The effect of the load mass and the maximum allowable tension of the cable on the workspace is examined by simulation.Results show that the lifting system has limited carrying capacity and a data reference for selecting the structural parameters by analyzing the factors affecting the workspace.Findings provide a basis for further research on the optimal design of structural parameters and the determination of safe configurations of the lifting system.
基金Foundation item： Supported by the National Natural Science Foundation of China （Grant nos. 50639030 and 50979070） and the 863 Program of China （Grant no. 2006AA09Z348）.
文摘Experimental and theoretical studies of drag embedment plate anchors recently carried out in Tianjin University are summarized in this research paper, which involve a series of important topics relevant to the study of drag anchors. The techniques for measuring the trajectory and movement direction of drag anchors in soils, the techniques for measuring the moving embedment point and reverse eatenary shape of the embedded drag line, the penetration mechanism and kinematic behavior of drag anchors, the ultimate embedment depth of drag anchors, the movement direction of the anchor with an arbitrary fluke section, the reverse catenary properties of the embedded drag line, the interaetional properties between drag anchor and installation line, the kinematic model of drag anchors in seabed soils, and the analytical method for predicting the anchor trajectory in soils will all be examined. The present work remarkably reduces the uncertainties in design and analysis of drag embedment plate anchors, and is beneficial to improving the application of this new type of drag anchor in offshore engineering.
