Since previous studies of parallel mechanisms (PMs) have tended to favor symmetrical overall configuration to obtain relatively stable kinematic and dynamic performance and to satisfy isotropic requirements. The analysis of kinematic and dynamic performance of asymmetric mechanisms has been an issue of interest. In this paper, an asymmetric SCARA-type PM with 4 degrees-of-freedom (DOF) is proposed. First, the orientation characteristic set is calculated to obtain the DOF of the PM. Then, the inverse kinematics and the velocity and acceleration of each branch chain of the mechanism is analyzed. The dynamic model of the mechanism is established according to the principle of virtual work. The workspace of the mechanism is drawn according to the constraints that have been given to the mechanism's kinematic pairs. The singularity, dexterity, motion/force transfer performance and maximum acceleration performance of the mechanism are also analyzed. On this basis, the kinematic and dynamic performance evaluation indexes of the mechanism are studied. Finally, the workspace and acceleration performance of the mechanism are optimized based on the differential evolution algorithm (DE) to obtain the structural parameters when the mechanism achieves optimal performance. The asymmetric PM proposed in this paper, as well as the algorithm of performance index and optimization method used can provide some reference value for configuration design and optimization analysis.
{"title":"Performance Analysis and Optimal Design of a Novel Schöenflies-Motion Asymmetric Parallel Mechanism","authors":"Wei Zhu, Xueyang Zhu, Zhiyuan Ma, Huiping Shen","doi":"10.1115/1.4062149","DOIUrl":"https://doi.org/10.1115/1.4062149","url":null,"abstract":"\u0000 Since previous studies of parallel mechanisms (PMs) have tended to favor symmetrical overall configuration to obtain relatively stable kinematic and dynamic performance and to satisfy isotropic requirements. The analysis of kinematic and dynamic performance of asymmetric mechanisms has been an issue of interest. In this paper, an asymmetric SCARA-type PM with 4 degrees-of-freedom (DOF) is proposed. First, the orientation characteristic set is calculated to obtain the DOF of the PM. Then, the inverse kinematics and the velocity and acceleration of each branch chain of the mechanism is analyzed. The dynamic model of the mechanism is established according to the principle of virtual work. The workspace of the mechanism is drawn according to the constraints that have been given to the mechanism's kinematic pairs. The singularity, dexterity, motion/force transfer performance and maximum acceleration performance of the mechanism are also analyzed. On this basis, the kinematic and dynamic performance evaluation indexes of the mechanism are studied. Finally, the workspace and acceleration performance of the mechanism are optimized based on the differential evolution algorithm (DE) to obtain the structural parameters when the mechanism achieves optimal performance. The asymmetric PM proposed in this paper, as well as the algorithm of performance index and optimization method used can provide some reference value for configuration design and optimization analysis.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43439532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Multistable origami and its snapping behaviors between the folded states have attracted scientists' and engineers' attention as the building block for the design of mechanical devices and metamaterials. We propose a novel method for designing origami-based multistable structures, by which we mean (1) to obtain the prescribed overall motion and (2) to control the stiffness of snapping provided by the elastic strain. We solve this design problem by first representing the desired motion with linkage structures with quadrilateral holes, called the frames, and then filling the frames with origami modules, called quadrilateral boundary modules. By introducing an intentional incompatibility between the motions of the frames and the modules, we design the snapping behavior that follows the linkage motion. We provide the representation model to evaluate the incompatibility and propose an optimization-based framework for the design. We also validate our design applied to a Sarrus-linkage through bar-and-hinge analysis and experiments using physical prototypes.
{"title":"Designing and Analyzing Multistable Mechanisms Using Quadrilateral Boundary Rigid Origami","authors":"Mun-jae Lee, Yuki Miyajima, Tomohiro Tachi","doi":"10.1115/1.4062132","DOIUrl":"https://doi.org/10.1115/1.4062132","url":null,"abstract":"\u0000 Multistable origami and its snapping behaviors between the folded states have attracted scientists' and engineers' attention as the building block for the design of mechanical devices and metamaterials. We propose a novel method for designing origami-based multistable structures, by which we mean (1) to obtain the prescribed overall motion and (2) to control the stiffness of snapping provided by the elastic strain. We solve this design problem by first representing the desired motion with linkage structures with quadrilateral holes, called the frames, and then filling the frames with origami modules, called quadrilateral boundary modules. By introducing an intentional incompatibility between the motions of the frames and the modules, we design the snapping behavior that follows the linkage motion. We provide the representation model to evaluate the incompatibility and propose an optimization-based framework for the design. We also validate our design applied to a Sarrus-linkage through bar-and-hinge analysis and experiments using physical prototypes.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42911230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiao Zhang, Xin Zhou, Ming Li, Tianming Liu, Jian Xing, Weilin Lv, Fufu Yang, Yan Chen
Multiple mobile assemblies have been created based on two-dimensional tessellations of linkages for deployable structures. However, few three-dimensional tessellations of linkages have been created, especially mobile assemblies with bifurcation. Here, we proposed four types of mobile assemblies of kaleidocycles, a special type of threefold-symmetric Bricard linkages, based on cubic cellulation and symmetry. Kinematic analysis of them is carried out based on the matrix method and numerical method. Two assemblies have bifurcations with two motion paths following cuboid symmetry and tetrahedral symmetry, respectively. Meanwhile, the other two have one motion path with single degree of freedom. The designing process facilitates the creation of new mobile assemblies under symmetry and the four assemblies have the potential application for designing metamaterials.
{"title":"Three-dimensional Mobile Assemblies based on Threefold-symmetric Bricard Linkages","authors":"Xiao Zhang, Xin Zhou, Ming Li, Tianming Liu, Jian Xing, Weilin Lv, Fufu Yang, Yan Chen","doi":"10.1115/1.4062131","DOIUrl":"https://doi.org/10.1115/1.4062131","url":null,"abstract":"\u0000 Multiple mobile assemblies have been created based on two-dimensional tessellations of linkages for deployable structures. However, few three-dimensional tessellations of linkages have been created, especially mobile assemblies with bifurcation. Here, we proposed four types of mobile assemblies of kaleidocycles, a special type of threefold-symmetric Bricard linkages, based on cubic cellulation and symmetry. Kinematic analysis of them is carried out based on the matrix method and numerical method. Two assemblies have bifurcations with two motion paths following cuboid symmetry and tetrahedral symmetry, respectively. Meanwhile, the other two have one motion path with single degree of freedom. The designing process facilitates the creation of new mobile assemblies under symmetry and the four assemblies have the potential application for designing metamaterials.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49207256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work introduces methods of developing embedded straight-line and linear-motion mechanisms on right circular cylinders. Developable surfaces, particularly right circular cylinders, are the manufactured embodiment of many products. Functional linkages are traditionally not geometrically constrained to a body and often dictate the final shape of the housing they reside in. This work explores the idea of mapping straight-line and linear-motion mechanisms onto cylinders for practical design purposes. Potential applications for when an embedded cylindrical developable mechanism capable of deployment and generation of linear motion would be useful are discussed. An in vivo wiper mechanism to clean obstructed laparoscope lenses during surgery is investigated to physically demonstrate the concepts introduced in the paper and to illustrate an example application.
{"title":"EMBEDDED LINEAR-MOTION DEVELOPABLE MECHANISMS ON CYLINDRICAL SURFACES","authors":"Jacob Sheffield, Brandon Sargent, L. Howell","doi":"10.1115/1.4062133","DOIUrl":"https://doi.org/10.1115/1.4062133","url":null,"abstract":"\u0000 This work introduces methods of developing embedded straight-line and linear-motion mechanisms on right circular cylinders. Developable surfaces, particularly right circular cylinders, are the manufactured embodiment of many products. Functional linkages are traditionally not geometrically constrained to a body and often dictate the final shape of the housing they reside in. This work explores the idea of mapping straight-line and linear-motion mechanisms onto cylinders for practical design purposes. Potential applications for when an embedded cylindrical developable mechanism capable of deployment and generation of linear motion would be useful are discussed. An in vivo wiper mechanism to clean obstructed laparoscope lenses during surgery is investigated to physically demonstrate the concepts introduced in the paper and to illustrate an example application.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46072099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hang Xiao, Jianyin Tang, Shengnan Lyu, Kun Xu, Xilun Ding
Cable-driven arms have the advantages of light weight, large workspace, good compliance, high speed and acceleration. This paper proposes a cable-driven variable stiffness humanoid arm that can reproduce typical daily postures of the upper limb with a few actuators via kinematic synergy. A kinematic model of the arm is established to obtain the design parameters corresponding to different postures. The dimension reduction of the actuation is realized through a synergy analysis of the driving cables. A coupling actuation mechanism is designed to reduce the number of actuators required to generate specific postures of the arm via cables. Optimization of the geometric parameters of the joints is conducted to improve the posture reproduction accuracy. The stiffness of the arm could be regulated by adjusting the cable tension. Stiffness modeling of the joint is performed to evaluate the influence of cable tension. A prototype of the arm is designed. The workspace is analyzed under the actuation of the designed coupling mechanism. The transformation among the targeted postures is simulated to validate the feasibility of the actuation dimension reduction design of the arm. Robustness analysis is conducted which indicates the use of synergic actuation weakens the arm robustness. With the proposed dimension reduction method, the actuation dimensions are reduced from 9 to 4, which leads to the diminution of reachable workspace and manipulability. The reproduction accuracy of the targeted postures is 90.4%. The proposed method can be applied to the dimension reduction designs of other cable-driven robots.
{"title":"Design and implementation of a synergy-based cable-driven humanoid arm with variable stiffness","authors":"Hang Xiao, Jianyin Tang, Shengnan Lyu, Kun Xu, Xilun Ding","doi":"10.1115/1.4062130","DOIUrl":"https://doi.org/10.1115/1.4062130","url":null,"abstract":"\u0000 Cable-driven arms have the advantages of light weight, large workspace, good compliance, high speed and acceleration. This paper proposes a cable-driven variable stiffness humanoid arm that can reproduce typical daily postures of the upper limb with a few actuators via kinematic synergy. A kinematic model of the arm is established to obtain the design parameters corresponding to different postures. The dimension reduction of the actuation is realized through a synergy analysis of the driving cables. A coupling actuation mechanism is designed to reduce the number of actuators required to generate specific postures of the arm via cables. Optimization of the geometric parameters of the joints is conducted to improve the posture reproduction accuracy. The stiffness of the arm could be regulated by adjusting the cable tension. Stiffness modeling of the joint is performed to evaluate the influence of cable tension. A prototype of the arm is designed. The workspace is analyzed under the actuation of the designed coupling mechanism. The transformation among the targeted postures is simulated to validate the feasibility of the actuation dimension reduction design of the arm. Robustness analysis is conducted which indicates the use of synergic actuation weakens the arm robustness. With the proposed dimension reduction method, the actuation dimensions are reduced from 9 to 4, which leads to the diminution of reachable workspace and manipulability. The reproduction accuracy of the targeted postures is 90.4%. The proposed method can be applied to the dimension reduction designs of other cable-driven robots.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44663648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a general equivalent approach to solve the stiffness modeling, or load-deformation problem of parallel mechanisms. Based on the principal axes decomposition of structure compliance matrices, an equivalent 6-DOF serial mechanism is established to approximate the load-deformation behavior of each flexible link in the mechanism. Hence, each limb of the parallel mech-anism can be equivalent to a serial redundant rigid body mechanism with passive elastic joints, and the load-deformation problem can be transformed to the equilibrium configuration calculation of the equivalent mechanism. The main advantage of the proposed method is that the robotic kinematics and statics, rather than the elastic mechanics, can be directly adopted to solve the equilibrium configura-tion of the parallel mechanism under external load. Besides, a closed form solution of the corre-sponding deformation can be obtained, which can be solved by the gradient-based searching algo-rithm. Therefore, the final deformation will no longer be linear to the external load, which makes this method more accurate and more suitable for the deformation prediction and compensation in real industrial working conditions. In order to verify the effectiveness and correctness of this method, a 3PRRU parallel manipulator will be introduced as an example, to compare the load-deformation results with the FEA simulation and matrix calculation methods, so the nonlinearity feature can be shown in an intuitive manner.
{"title":"Stiffness Modeling and Deformation Analysis of Parallel Manipulators Based on the Principal Axes Decomposition of Compliance Matrices","authors":"Shuangshuang Zhang, Linsong Zhang","doi":"10.1115/1.4062134","DOIUrl":"https://doi.org/10.1115/1.4062134","url":null,"abstract":"\u0000 This paper presents a general equivalent approach to solve the stiffness modeling, or load-deformation problem of parallel mechanisms. Based on the principal axes decomposition of structure compliance matrices, an equivalent 6-DOF serial mechanism is established to approximate the load-deformation behavior of each flexible link in the mechanism. Hence, each limb of the parallel mech-anism can be equivalent to a serial redundant rigid body mechanism with passive elastic joints, and the load-deformation problem can be transformed to the equilibrium configuration calculation of the equivalent mechanism. The main advantage of the proposed method is that the robotic kinematics and statics, rather than the elastic mechanics, can be directly adopted to solve the equilibrium configura-tion of the parallel mechanism under external load. Besides, a closed form solution of the corre-sponding deformation can be obtained, which can be solved by the gradient-based searching algo-rithm. Therefore, the final deformation will no longer be linear to the external load, which makes this method more accurate and more suitable for the deformation prediction and compensation in real industrial working conditions. In order to verify the effectiveness and correctness of this method, a 3PRRU parallel manipulator will be introduced as an example, to compare the load-deformation results with the FEA simulation and matrix calculation methods, so the nonlinearity feature can be shown in an intuitive manner.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48220752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract For successful push recovery in response to perturbations, a humanoid robot must select an appropriate stabilizing action. Existing approaches are limited because they are often derived from reduced-order models that ignore system-specific aspects such as swing leg dynamics or kinematic and actuation limits. In this study, the formulation of capturability for whole-body humanoid robots is introduced as a partition-based approach in the augmented center-of-mass (COM)-state space. The 1-step capturable boundary is computed from an optimization-based method that incorporates whole-body system properties with full-order nonlinear system dynamics in the sagittal plane including contact interactions with the ground and conditions for achieving a complete stop after stepping. The 1-step capturable boundary, along with the balanced state boundaries, are used to quantify the relative contributions of different strategies and contacts in maintaining or recovering balance in push recovery. The computed boundaries are also incorporated as explicit criteria into a partition-aware push recovery controller that monitors the robot’s COM state to selectively exploit the ankle, hip, or captured stepping strategies. The push recovery simulation experiments demonstrated the validity of the stability boundaries in fully exploiting a humanoid robot’s balancing capability through appropriate balancing actions in response to perturbations. Overall, the system-specific capturability with the whole-body system properties and dynamics outperformed that derived from a typical reduced-order model.
{"title":"Partition-Aware Stability Control for Humanoid Robot Push Recovery With Whole-Body Capturability","authors":"Hyunjong Song, William Peng, Joo H. Kim","doi":"10.1115/1.4056956","DOIUrl":"https://doi.org/10.1115/1.4056956","url":null,"abstract":"Abstract For successful push recovery in response to perturbations, a humanoid robot must select an appropriate stabilizing action. Existing approaches are limited because they are often derived from reduced-order models that ignore system-specific aspects such as swing leg dynamics or kinematic and actuation limits. In this study, the formulation of capturability for whole-body humanoid robots is introduced as a partition-based approach in the augmented center-of-mass (COM)-state space. The 1-step capturable boundary is computed from an optimization-based method that incorporates whole-body system properties with full-order nonlinear system dynamics in the sagittal plane including contact interactions with the ground and conditions for achieving a complete stop after stepping. The 1-step capturable boundary, along with the balanced state boundaries, are used to quantify the relative contributions of different strategies and contacts in maintaining or recovering balance in push recovery. The computed boundaries are also incorporated as explicit criteria into a partition-aware push recovery controller that monitors the robot’s COM state to selectively exploit the ankle, hip, or captured stepping strategies. The push recovery simulation experiments demonstrated the validity of the stability boundaries in fully exploiting a humanoid robot’s balancing capability through appropriate balancing actions in response to perturbations. Overall, the system-specific capturability with the whole-body system properties and dynamics outperformed that derived from a typical reduced-order model.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136178992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhengyu Wang, Shiyang Bao, Bin Zi, Zirui Jia, Xiang Yu
This paper presents the design, analysis, and development of a novel four degrees of freedom (4-DOF) endoscopic robot with cable-driven multi-segment flexible continuum mechanisms. The endoscopic robot is mainly composed of the passive positioning arm, cable-pulley system and 3-DOF flexible continuum mechanism. The forward and inverse kinematics of the endoscopic robot are derived based on the constant curvature assumption, and its working space, flexibility and preoperative incision determination method are analyzed as well. Based on the hardware structure of the robot system, a control strategy and a control software are developed, and the continuum mechanism is kinematically calibrated to carry out the trajectory planning experiment and simulated surgery experiment. The experimental results show that the calibrated constant curvature model can be used for the motion control of the continuum mechanism, and the 4-DOF endoscopic robot can meet the visual field requirements of minimally invasive surgery.
{"title":"Development of a Novel 4-DOF Flexible Endoscopic Robot Using Cable-driven Multi-segment Continuum Mechanisms","authors":"Zhengyu Wang, Shiyang Bao, Bin Zi, Zirui Jia, Xiang Yu","doi":"10.1115/1.4057075","DOIUrl":"https://doi.org/10.1115/1.4057075","url":null,"abstract":"This paper presents the design, analysis, and development of a novel four degrees of freedom (4-DOF) endoscopic robot with cable-driven multi-segment flexible continuum mechanisms. The endoscopic robot is mainly composed of the passive positioning arm, cable-pulley system and 3-DOF flexible continuum mechanism. The forward and inverse kinematics of the endoscopic robot are derived based on the constant curvature assumption, and its working space, flexibility and preoperative incision determination method are analyzed as well. Based on the hardware structure of the robot system, a control strategy and a control software are developed, and the continuum mechanism is kinematically calibrated to carry out the trajectory planning experiment and simulated surgery experiment. The experimental results show that the calibrated constant curvature model can be used for the motion control of the continuum mechanism, and the 4-DOF endoscopic robot can meet the visual field requirements of minimally invasive surgery.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44503938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiaming Fu, Ziqing Yu, Han Lin, Lianxi Zheng, Dongming Gan
Abstract Variable stiffness manipulators balance the trade-off between manipulation performance needing high stiffness and safe human–robot interaction desiring low stiffness. Variable stiffness links enable this flexible manipulation function during human–robot interaction. In this paper, we propose a novel variable stiffness link based on discrete variable stiffness units (DSUs). A DSU is a parallel guided beam that can adjust stiffness discretely by changing the cross-sectional area properties of the hollow beam segments. The variable stiffness link (Tri-DSU) consists of three tandem DSUs to achieve eight stiffness modes and a stiffness ratio of 31. To optimize the design, stiffness analysis of the DSU and Tri-DSU under various configurations and forces was performed by a derived linear analytical model which applies to small/intermediate deflections. The model is derived using the approach of serially connected beams and superposition combinations. 3D-Printed prototypes were built to verify the feature and performance of the Tri-DSU in comparison with the finite element analysis and analytical model results. It’s demonstrated that our model can accurately predict the stiffnesses of the DSU and Tri-DSU within a certain range of parameters. Impact tests were also conducted to validate the performance of the Tri-DSU. The developed method and analytical model are extendable to multiple DSUs with parameter configurations to achieve modularization and customization, and also provide a tool for the design of reconfigurable collaborative robot (cobot) manipulators.
{"title":"A Novel Variable Stiffness Compliant Robotic Link Based on Discrete Variable Stiffness Units for Safe Human–Robot Interaction","authors":"Jiaming Fu, Ziqing Yu, Han Lin, Lianxi Zheng, Dongming Gan","doi":"10.1115/1.4056957","DOIUrl":"https://doi.org/10.1115/1.4056957","url":null,"abstract":"Abstract Variable stiffness manipulators balance the trade-off between manipulation performance needing high stiffness and safe human–robot interaction desiring low stiffness. Variable stiffness links enable this flexible manipulation function during human–robot interaction. In this paper, we propose a novel variable stiffness link based on discrete variable stiffness units (DSUs). A DSU is a parallel guided beam that can adjust stiffness discretely by changing the cross-sectional area properties of the hollow beam segments. The variable stiffness link (Tri-DSU) consists of three tandem DSUs to achieve eight stiffness modes and a stiffness ratio of 31. To optimize the design, stiffness analysis of the DSU and Tri-DSU under various configurations and forces was performed by a derived linear analytical model which applies to small/intermediate deflections. The model is derived using the approach of serially connected beams and superposition combinations. 3D-Printed prototypes were built to verify the feature and performance of the Tri-DSU in comparison with the finite element analysis and analytical model results. It’s demonstrated that our model can accurately predict the stiffnesses of the DSU and Tri-DSU within a certain range of parameters. Impact tests were also conducted to validate the performance of the Tri-DSU. The developed method and analytical model are extendable to multiple DSUs with parameter configurations to achieve modularization and customization, and also provide a tool for the design of reconfigurable collaborative robot (cobot) manipulators.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136178991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Binbin Lian, Pan Feng, Jin Wu, J. Ma, Yuan Zhang, Yimin Song
Interior assembling inside the cabin of an aircraft requires assembling robot to be light-weight and able to carry heavy payload. This paper proposed a hybrid robot, carried out its optimal design and experiments. The robot consists of a 1T2R parallel module and a 2T serial module. In the parallel module, the 1st limb is composed of a slider-crank mechanism and a RS link. The other two limbs are PRS limbs. Herein, R, S, P are revolute, spherical and actuated prismatic joints. Optimization of the robot concerns motion/force transmissibility, total mass and stiffness. Hence, kinematic, stiffness and mass modeling are implemented, and then the Pareto-based multi-objective optimization. Objective arrangements are discussed by concerning (1) the conflicting relation between mass and the minimal linear stiffness along z-axis, and (2) the overall stiffness performance. After comparing six multi-objective optimizations, it is found that simultaneously regarding mass and minimal linear stiffness along z-axis as objectives is beneficial for obtaining large payload-to-mass ratio. Moreover, having overall stiffness as objectives would lower the values of motion/force transmissibility and payload-to-mass ratio. Finally, optimization model having motion/force transmissibility, total mass and minimal linear stiffness along z-axis as objectives is selected. The optimal payload-to-mass ratio is up to 13.2837. The 5-DoF hybrid robot is machined and assembled. Experiments on the workspace, repeatability and load carrying capacity confirm the performances of the designed robot.
{"title":"Light-weight Design of 5-DoF hybrid robot for assembling in the cabin","authors":"Binbin Lian, Pan Feng, Jin Wu, J. Ma, Yuan Zhang, Yimin Song","doi":"10.1115/1.4057074","DOIUrl":"https://doi.org/10.1115/1.4057074","url":null,"abstract":"\u0000 Interior assembling inside the cabin of an aircraft requires assembling robot to be light-weight and able to carry heavy payload. This paper proposed a hybrid robot, carried out its optimal design and experiments. The robot consists of a 1T2R parallel module and a 2T serial module. In the parallel module, the 1st limb is composed of a slider-crank mechanism and a RS link. The other two limbs are PRS limbs. Herein, R, S, P are revolute, spherical and actuated prismatic joints. Optimization of the robot concerns motion/force transmissibility, total mass and stiffness. Hence, kinematic, stiffness and mass modeling are implemented, and then the Pareto-based multi-objective optimization. Objective arrangements are discussed by concerning (1) the conflicting relation between mass and the minimal linear stiffness along z-axis, and (2) the overall stiffness performance. After comparing six multi-objective optimizations, it is found that simultaneously regarding mass and minimal linear stiffness along z-axis as objectives is beneficial for obtaining large payload-to-mass ratio. Moreover, having overall stiffness as objectives would lower the values of motion/force transmissibility and payload-to-mass ratio. Finally, optimization model having motion/force transmissibility, total mass and minimal linear stiffness along z-axis as objectives is selected. The optimal payload-to-mass ratio is up to 13.2837. The 5-DoF hybrid robot is machined and assembled. Experiments on the workspace, repeatability and load carrying capacity confirm the performances of the designed robot.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45102049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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