Abstract. The face gear tooth surface is a high-order variable curvature surface, and the curvature of the surface is complicated, so it is difficult to describe the characteristics of the face gear tooth surface by a specific equation. In this paper, the discrete curvature relation of the surface is used instead of an analytical equation to describe a spatial meshing surface, and the traditional meshing theory is neutralized to analyze the characteristics of the face gear tooth surface. Firstly, according to the structural characteristics of the face gear, the sampling method of the face gear tooth surface is analyzed, and the mathematical model of fitting the tooth surface contact point is established. Then, the discrete asymptotic surface development analysis method is studied, and the ellipsoid contact analysis method of the face gear pair is established by simplifying the conjugate surface and its region. Finally, the contact analysis method of the discrete tooth surface is studied, and the instantaneous contact ellipse of the face gear tooth surface is calculated, which formed a new numerical meshing method of space curved surface.
{"title":"Ellipsoid contact analysis and application in the surface conjugate theory of face gears","authors":"Xiao-meng Chu, Yalin Liu, H. Zeng","doi":"10.5194/ms-14-305-2023","DOIUrl":"https://doi.org/10.5194/ms-14-305-2023","url":null,"abstract":"Abstract. The face gear tooth surface is a high-order variable curvature surface, and the curvature of the surface is complicated, so it is difficult to describe the characteristics of the face gear tooth surface by a specific equation. In this paper, the discrete curvature relation of the surface is used instead of an analytical equation to describe a spatial meshing surface, and the traditional meshing theory is neutralized to analyze the characteristics of the face gear tooth surface. Firstly, according to the structural characteristics of the face gear, the sampling method of the face gear tooth surface is analyzed, and the mathematical model of fitting the tooth surface contact point is established. Then, the discrete asymptotic surface development analysis method is studied, and the ellipsoid contact analysis method of the face gear pair is established by\u0000simplifying the conjugate surface and its region. Finally, the contact analysis method of the discrete tooth surface is studied, and the\u0000instantaneous contact ellipse of the face gear tooth surface is calculated, which formed a new numerical meshing method of space curved surface.\u0000","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45547862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. A robust position control algorithm with learning feedback gain automatic adjustment for collaborative robots under uncertainty is proposed, aiming to compensate for the disturbance effects of the system. First, inside the proportional-derivative (PD) control framework, the robust controller is designed based on model and error. All of the model's uncertainties are represented by functions with upper bounds in order to surmount the uncertainties induced by parameter changes and unmodeled dynamics. Secondly, the feedback gain is automatically adjusted by learning, so that the control feedback gain is automatically adjusted iteratively to optimize the desired performance of the system. Thirdly, the Lyapunov minimax method is used to demonstrate that the proposed controller is both uniformly bounded and uniformly ultimately bounded. The simulations and experimental results of the robot experimental platform demonstrate that the proposed control achieves outstanding performance in both transient and steady-state tracking. Also, the proposed control has a simple structure with few parameters requiring adjustment, and no manual setting is required during parameter setting. Moreover, the robustness and efficacy of the robot's trajectory tracking with uncertainty are significantly enhanced.
{"title":"Robust trajectory tracking control for collaborative robots based on learning feedback gain self-adjustment","authors":"Xiaoxiao Liu, Mengyuan Chen","doi":"10.5194/ms-14-293-2023","DOIUrl":"https://doi.org/10.5194/ms-14-293-2023","url":null,"abstract":"Abstract. A robust position control algorithm with learning feedback gain automatic adjustment for collaborative robots under uncertainty is proposed, aiming to compensate for the disturbance effects of the system. First, inside the proportional-derivative (PD) control framework, the robust controller is designed based on model and error. All of the model's uncertainties are represented by functions with upper bounds in order to surmount the uncertainties\u0000induced by parameter changes and unmodeled dynamics. Secondly, the feedback\u0000gain is automatically adjusted by learning, so that the control feedback\u0000gain is automatically adjusted iteratively to optimize the desired\u0000performance of the system. Thirdly, the Lyapunov minimax method is used to\u0000demonstrate that the proposed controller is both uniformly bounded and\u0000uniformly ultimately bounded. The simulations and experimental results of the\u0000robot experimental platform demonstrate that the proposed control achieves\u0000outstanding performance in both transient and steady-state tracking. Also,\u0000the proposed control has a simple structure with few parameters requiring adjustment, and no manual setting is required during parameter setting. Moreover, the robustness and efficacy of the robot's trajectory tracking\u0000with uncertainty are significantly enhanced.\u0000","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43109056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. In order to reduce the resistance and increase speed for a high-speed wheeled amphibious vehicle, a wheel-retracting mechanism was applied to a walking mechanism and the influence was researched. Firstly, to obtain a reliable numerical method, a realizable shear stress transport (SST) k-ω turbulence model and computational fluid dynamic (CFD) model built by an overset mesh technique was used and compared with the corresponding model tests. Secondly, the effect of the wheels' flip angle on resistance, heave and pitch was investigated. Then, the wheel well was optimized by numerical simulation. Finally, the results showed that the influence of the wheels on resistance was more significant, and the larger the wheels' flip angle was, the more significant the resistance reduction would be. An optimized wheel well was beneficial to resistance reduction. Furthermore, the running attitude became steadier, thereby decreasing the heave and pitch.
{"title":"Influence of a walking mechanism on the hydrodynamic performance of a high-speed wheeled amphibious vehicle","authors":"Haijun Xu, Liyang Xu, Y. Feng, Xiaojun Xu, Yue Jiang, Xue Gao","doi":"10.5194/ms-14-277-2023","DOIUrl":"https://doi.org/10.5194/ms-14-277-2023","url":null,"abstract":"Abstract. In order to reduce the resistance and increase speed for\u0000a high-speed wheeled amphibious vehicle, a wheel-retracting mechanism was\u0000applied to a walking mechanism and the influence was researched. Firstly, to\u0000obtain a reliable numerical method, a realizable shear stress transport (SST) k-ω turbulence\u0000model and computational fluid dynamic (CFD) model built by an overset mesh technique was used and compared\u0000with the corresponding model tests. Secondly, the effect of the wheels' flip\u0000angle on resistance, heave and pitch was investigated. Then, the wheel well\u0000was optimized by numerical simulation. Finally, the results showed that the\u0000influence of the wheels on resistance was more significant, and the larger\u0000the wheels' flip angle was, the more significant the resistance reduction\u0000would be. An optimized wheel well was beneficial to resistance reduction.\u0000Furthermore, the running attitude became steadier, thereby decreasing the\u0000heave and pitch.\u0000","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45918427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rui Liu, Yishan Zeng, Min Hu, Huabing Zhu, Changhai Liu, Lei Wang
Abstract. In pursuit of design solutions that reduce energy loss and improve wear resistance for the piston–cylinder interface in an axial piston motor, a fluid-structure interaction numerical model and a new test rig of the friction force of the piston–cylinder pair are developed to achieve the analysis and design of the micro-geometric tapered-shape surface of a piston bore. The piston bore with the tapered-shape surface axial distribution length ratio of 49.44 % of the overall length is found to be the relatively optimized one. Furthermore, how the shaft speed, load pressure, and swash plate angle influence the performance of the two-type interface is analyzed. Numerical analysis results show that, compared with the traditional cylindrical piston bore design, the piston–cylinder interface with the optimized tapered-shape piston bore in the axial piston motor can achieve a significant reduction in leakage flow and friction force, and the experimental results are consistent with the simulation results.
{"title":"An investigation into the micro-geometric tapered-shape surface design of the piston bore of a piston–cylinder interface in an axial piston motor","authors":"Rui Liu, Yishan Zeng, Min Hu, Huabing Zhu, Changhai Liu, Lei Wang","doi":"10.5194/ms-14-259-2023","DOIUrl":"https://doi.org/10.5194/ms-14-259-2023","url":null,"abstract":"Abstract. In pursuit of design solutions that reduce energy loss and improve wear resistance for the piston–cylinder interface in an axial piston motor, a fluid-structure interaction numerical model and a new test rig of the friction force of the piston–cylinder pair are developed to achieve the analysis and design of the micro-geometric tapered-shape surface of a piston bore. The piston bore with the tapered-shape surface axial distribution length ratio of 49.44 % of the overall length is found to be the relatively optimized one. Furthermore, how the shaft speed, load pressure, and swash plate angle influence the performance of the two-type interface is analyzed. Numerical analysis results show that, compared with the traditional cylindrical piston bore design, the piston–cylinder interface with the optimized tapered-shape piston bore in the axial piston motor can achieve a significant reduction in leakage flow and friction force, and the experimental results are consistent with the simulation results.\u0000","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43013654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. In order to solve the problems of low path-tracking accuracy, poor safety, and stability of intelligent vehicles with variable speeds and obstacles on the road, a double-layer adaptive model predictive controller (MPC) is designed. A vehicle point mass model is used in an obstacle avoidance planning controller, and the safety collision distance model is established according to the distance relationship between the vehicle and the obstacle to improve the driving safety of the vehicle. The design of the path-tracking controller is based on the three-degrees-of-freedom dynamics model. According to the relationship between the predictive horizon and vehicle speed in the MPC algorithm, an adaptive path-tracking control strategy which can update the prediction horizon in real time is proposed to improve the accuracy of vehicle path tracking. To increase the vehicle stability, a sideslip angle and an acceleration control variable are added to the vehicle dynamics model as soft constraint conditions. The proposed method is simulated based on a CarSim and MATLAB/Simulink co-simulation platform. The simulation results show that the maximum lateral path deviation and the maximum centroid sideslip angle of the designed controller are 0.13 m and 0.4∘, respectively. Compared with the traditional MPC, the adaptive MPC maximum lateral path deviation and the maximum centroid sideslip angle are reduced by 0.51 m and 1.57∘, respectively, which proves the effectiveness of the proposed method.
{"title":"Intelligent vehicle obstacle avoidance path-tracking control based on adaptive model predictive control","authors":"Baorui Miao, Chao Han","doi":"10.5194/ms-14-247-2023","DOIUrl":"https://doi.org/10.5194/ms-14-247-2023","url":null,"abstract":"Abstract. In order to solve the problems of low path-tracking accuracy, poor safety, and stability of intelligent vehicles with variable speeds and obstacles on the road, a double-layer adaptive model predictive controller (MPC) is\u0000designed. A vehicle point mass model is used in an obstacle avoidance planning controller, and the safety collision distance model is established according to the distance relationship between the vehicle and the obstacle to improve the driving safety of the vehicle. The design of the path-tracking controller is based on the three-degrees-of-freedom dynamics model. According to\u0000the relationship between the predictive horizon and vehicle speed in the MPC algorithm, an adaptive path-tracking control strategy which can update the prediction horizon in real time is proposed to improve the accuracy of vehicle path tracking. To increase the vehicle stability, a sideslip angle and an acceleration control variable are added to the vehicle\u0000dynamics model as soft constraint conditions. The proposed method is simulated based on a CarSim and MATLAB/Simulink co-simulation platform. The simulation results show that the maximum lateral path deviation and the\u0000maximum centroid sideslip angle of the designed controller are 0.13 m and\u00000.4∘, respectively. Compared with the traditional MPC, the adaptive MPC maximum lateral path deviation\u0000and the maximum centroid sideslip angle are reduced by 0.51 m and\u00001.57∘, respectively, which proves the effectiveness of the\u0000proposed method.\u0000","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44584943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qingxiong Lu, ChaoĀ Li, Yangyang Zhang, H. Fang, G. Bin
Abstract. In the complex environment of the battlefield and dust weather, hard objects including birds, bullets, sand and others will inevitably cause impact damage to the compressor blades of turboshaft engines. The damage will further result in fatigue vibration of the gas generator rotor and catastrophic accidents such as excessive engine vibration and even crash. The relation between oil film clearance of dampers and damping of rotor systems as well as the damping and vibration amplitude of a rotor system are analyzed. The functional relation between oil film clearance and vibration amplitude is derived. Taking the gas generator rotor of a certain turboshaft engine as an example, the rotor dynamic model of a gas generator rotor with oil film bearing clearance is constructed, and the vibration response of the rotor system under different oil film clearances is analyzed. A new type of squeeze film damper (SFD) structure with piezoelectric-driven split pads is innovatively designed, and the vibration control system of the gas generator rotor is built. In addition, experimental research on rotor fault vibration control under different oil film clearances is carried out. The results show that, within a certain range, when oil film clearance decreases, amplitude will decrease. Under the experimental conditions, when the driving voltage of the piezoelectric actuator is adjusted from 0 to 70 V, the oil film clearance decreases from 156 to 118 µm. Then, the vibration amplitude decreases and gradually reaches stability after 0.036 s, and the vibration amplitude of the rotor system decreases by 12 %. When the driving voltage of the piezoelectric actuator is adjusted to 150 V, the oil film clearance decreases to 76 µm, and the vibration amplitude of the rotor system decreases by 28 %. When the new SFD adopts a piezoelectric-driven split-pad structure, the structure can adjust quickly the oil film clearance online so as to control the vibration of the rotor system. The research results can provide a technical reference for the vibration control of turboshaft engine rotor systems.
{"title":"Study on the vibration control method of a turboshaft engine rotor based on piezoelectric squeeze film damper oil film clearance","authors":"Qingxiong Lu, ChaoĀ Li, Yangyang Zhang, H. Fang, G. Bin","doi":"10.5194/ms-14-237-2023","DOIUrl":"https://doi.org/10.5194/ms-14-237-2023","url":null,"abstract":"Abstract. In the complex environment of the battlefield and dust weather, hard objects including birds, bullets, sand and others will\u0000inevitably cause impact damage to the compressor blades of turboshaft\u0000engines. The damage will further result in fatigue vibration of the gas\u0000generator rotor and catastrophic accidents such as excessive engine\u0000vibration and even crash. The relation between oil film clearance of dampers and damping of rotor systems as well as the damping and vibration amplitude of\u0000a rotor system are analyzed. The functional relation between oil film\u0000clearance and vibration amplitude is derived. Taking the gas generator rotor\u0000of a certain turboshaft engine as an example, the rotor dynamic model of a gas generator rotor with oil film bearing clearance is constructed, and the\u0000vibration response of the rotor system under different oil film clearances\u0000is analyzed. A new type of squeeze film damper (SFD) structure with\u0000piezoelectric-driven split pads is innovatively designed, and the vibration control system of the gas generator rotor is built. In addition, experimental research on rotor fault vibration control under different oil\u0000film clearances is carried out. The results show that, within a certain range, when oil film clearance decreases, amplitude will decrease. Under the\u0000experimental conditions, when the driving voltage of the piezoelectric\u0000actuator is adjusted from 0 to 70 V, the oil film clearance decreases from\u0000156 to 118 µm. Then, the vibration amplitude decreases and\u0000gradually reaches stability after 0.036 s, and the vibration amplitude of\u0000the rotor system decreases by 12 %. When the driving voltage of the\u0000piezoelectric actuator is adjusted to 150 V, the oil film clearance\u0000decreases to 76 µm, and the vibration amplitude of the rotor system\u0000decreases by 28 %. When the new SFD adopts a piezoelectric-driven split-pad structure, the structure can adjust quickly the oil film clearance\u0000online so as to control the vibration of the rotor system. The research results can provide a technical reference for the vibration control of turboshaft\u0000engine rotor systems.\u0000","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49107473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yanding Guo, D. Wei, T. Gang, Xining Lai, X. Yang, G. Xiao, Lijie Chen
Abstract. Based on the bidirectional evolutionary structural optimization (BESO) method, the present article proposes an optimization method for a thermal structure involving design-dependent convective boundaries. Because the BESO method is incapable of keeping track of convection boundaries, virtual elements are introduced to assist in identifying the convection boundaries of the structure. In order to solve the difficult issue of element assignment under a design-dependent convection boundary, label matrixes are employed to modify the heat transfer matrix and the equivalent temperature load vector of elements over topology iterations. Additionally, the optimization objective is set to minimize the maximum temperature of the structure in order to deal with the objective reasonableness, and the p-norm method is then used to fit the objective function to calculate sensitivity. Finally, several cases, including 2D and 3D structures under various heat transfer boundary conditions, are provided to illustrate the effectiveness and good convergence of the proposed method.
{"title":"Topology optimization for thermal structures considering design-dependent convection boundaries based on the bidirectional evolutionary structural optimization method","authors":"Yanding Guo, D. Wei, T. Gang, Xining Lai, X. Yang, G. Xiao, Lijie Chen","doi":"10.5194/ms-14-223-2023","DOIUrl":"https://doi.org/10.5194/ms-14-223-2023","url":null,"abstract":"Abstract. Based on the bidirectional evolutionary structural optimization (BESO) method, the present article proposes an optimization\u0000method for a thermal structure involving design-dependent convective\u0000boundaries. Because the BESO method is incapable of keeping track of\u0000convection boundaries, virtual elements are introduced to assist in\u0000identifying the convection boundaries of the structure. In order to solve the\u0000difficult issue of element assignment under a design-dependent convection boundary,\u0000label matrixes are employed to modify the heat transfer matrix and the\u0000equivalent temperature load vector of elements over topology iterations.\u0000Additionally, the optimization objective is set to minimize the maximum\u0000temperature of the structure in order to deal with the objective reasonableness, and\u0000the p-norm method is then used to fit the objective function to calculate\u0000sensitivity. Finally, several cases, including 2D and 3D structures under\u0000various heat transfer boundary conditions, are provided to illustrate the\u0000effectiveness and good convergence of the proposed method.\u0000","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47652192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Safety in human–robot physical interaction and cooperation is of paramount interest. In this work, a human–humanoid interaction and cooperation scenario is considered. The robot arm is controlled by a proportional derivative (PD) controller in combination with an inherently fault-tolerant sliding-mode controller. During normal operation, if any of the joints of the robot arm develops a fault, the robot arm end effector may go into chaotic and dangerous motion. If such a scenario occurs, it poses a serious danger to the human in the loop as well as the robot. In this paper, an adaptive chaos sliding-mode controller is proposed to recover the tracking of the end effector when a fault occurs in any of the actuators. This tracking restoration is very important to complete a safety-critical task. The proposed scheme may help in addressing some safety issues arising from a joint failure, allowing it to finish the task at hand and stop it from going into a dangerous situation. The scheme is tested in simulation on the four degrees of freedom (DOF) model of the Bristol Robotics Laboratory (BRL) robot arm. Simulation results show efficient tracking recovery after a joint actuator failure. The controller demonstrated good performance in terms of tracking and stability when dealing with different joint actuator failures.
{"title":"Adaptive chaos control of a humanoid robot arm: a fault-tolerant scheme","authors":"S. G. Khan","doi":"10.5194/ms-14-209-2023","DOIUrl":"https://doi.org/10.5194/ms-14-209-2023","url":null,"abstract":"Abstract. Safety in human–robot physical interaction and cooperation is of paramount interest.\u0000In this work, a human–humanoid interaction and cooperation scenario is considered. The robot arm is controlled by a proportional derivative (PD) controller in combination with an inherently fault-tolerant sliding-mode controller.\u0000During normal operation, if any of the joints of the robot arm develops a fault, the robot arm end effector may go into chaotic and dangerous motion. If such a scenario occurs, it poses a serious danger to the human in the loop as well as the robot. In this paper, an adaptive chaos sliding-mode controller is proposed to recover the tracking of the end effector when a fault occurs in any of the actuators. This tracking restoration is very important to complete a safety-critical task. The proposed scheme may help in addressing some safety issues arising from a joint failure, allowing it to finish the task at hand and stop it from going into a dangerous situation. The scheme is tested in simulation on the four degrees of freedom (DOF) model of the Bristol Robotics Laboratory (BRL) robot arm. Simulation results show efficient tracking recovery after a joint actuator failure. The controller demonstrated good performance in terms of tracking and stability when dealing with different joint actuator failures.\u0000","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43133941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. In this paper, the authors developed a double-layer ring truss deployable antenna mechanism (RTDAM) based on a scissor unit, which can be used as the deployment and support mechanism in large-aperture satellite antenna. Firstly, three configuration state diagrams of the scissor multi-rod RTDAM were displayed: folded, half-deployed, and deployed. The mechanism was decomposed into a closed-ring deployable mechanism unit and several non-closed-ring deployable mechanism units. The screw constraint topological diagram of the closed-ring deployable mechanism unit was drawn, and the number of degrees of freedom (DOFs) was calculated via the screw theory method. Then, the expressions for screw velocity and screw acceleration of each component in the resultant mechanism were analyzed, calculated, and solved. The screw velocity and screw acceleration of each component were obtained, and the six-dimensional velocity and acceleration of each component were obtained through screw conversion and recursion. Finally, using the Newton–Euler equation and virtual work principle, the dynamic equation of the RTDAM with an integral scissor multi-rod ring truss mechanism was established, and the theoretical analysis was validated through numerical calculation and simulation results. The RTDAM of the scissor multi-rod ring truss proposed in this paper has a single DOF and can be well applied to the large-aperture satellite antenna.
{"title":"Kinematic and dynamic characteristics' analysis of a scissor multi-rod ring deployable mechanism","authors":"Bo Han, Yuxian Yao, Yuanzhi Zhou, Yundou Xu, Jiantao Yao, Yongsheng Zhao","doi":"10.5194/ms-14-193-2023","DOIUrl":"https://doi.org/10.5194/ms-14-193-2023","url":null,"abstract":"Abstract. In this paper, the authors developed a double-layer ring truss deployable antenna mechanism (RTDAM) based on a scissor unit, which can be used as the deployment and support mechanism in large-aperture satellite antenna. Firstly, three configuration state diagrams of the scissor multi-rod RTDAM were displayed: folded, half-deployed, and deployed. The mechanism was decomposed into a closed-ring deployable mechanism unit and several non-closed-ring deployable mechanism units. The screw constraint topological diagram of the closed-ring deployable mechanism unit was drawn, and the number of degrees of freedom (DOFs) was calculated via the screw theory method. Then, the expressions for screw velocity and screw acceleration of each component in the resultant mechanism were analyzed, calculated, and solved. The screw velocity and screw acceleration of each component were obtained, and the six-dimensional velocity and acceleration of each component were obtained through screw conversion and recursion. Finally, using the Newton–Euler equation and virtual work principle, the dynamic equation of the RTDAM with an integral scissor multi-rod ring truss mechanism was established, and the theoretical analysis was validated through numerical calculation and simulation results. The RTDAM of the scissor multi-rod ring truss proposed in this paper has a single DOF and can be well applied to the large-aperture satellite antenna.\u0000","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44522692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Mechanisms are prone to stuttering or even jamming due to the deformation of components, especially for overconstrained linkages for which geometric conditions must be strictly satisfied. In this paper, joint clearance is actively introduced to release the local constraint so that the linkages can still achieve general movement under the deformation of components. And a joint clearance model with a revolute joint (R-joint) is built. Based on the model, the minimum joint clearance introduced, which keeps mechanisms moving smoothly, is found when the components of the linkages have a certain deformation. The correctness of the proposed method is verified with a numerical case, and the optimal position for clearance introducing is analyzed. It opens up an important way to solve the phenomenon of stuttering or jamming in overconstrained linkages.
{"title":"Synthesis of clearance for a kinematic pair to prevent an overconstrained linkage from becoming stuck","authors":"Jian Qi, Yuan Gao, Fufu Yang","doi":"10.5194/ms-14-171-2023","DOIUrl":"https://doi.org/10.5194/ms-14-171-2023","url":null,"abstract":"Abstract. Mechanisms are prone to stuttering or even jamming due to the deformation of components, especially for overconstrained linkages for which geometric conditions must be strictly satisfied. In this paper, joint clearance is actively introduced to release the local constraint so that the linkages can still achieve general movement under the deformation of components. And a joint clearance model with a revolute joint (R-joint) is built. Based on the model, the minimum joint clearance introduced, which keeps mechanisms moving smoothly, is found when the components of the linkages have a certain deformation. The correctness of the proposed method is verified with a numerical case, and the optimal position for clearance introducing is analyzed. It opens up an important way to solve the phenomenon of stuttering or jamming in overconstrained linkages.\u0000","PeriodicalId":18413,"journal":{"name":"Mechanical Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42135294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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