Pub Date : 2025-01-08DOI: 10.1016/j.mechmachtheory.2024.105904
Anton Antonov, Alexey Fomin, Sergey Kiselev
This article considers an inverse and forward kinematic analysis of a recently proposed foldable parallel mechanism with a circular rail (FoldRail mechanism). The mechanism has six degrees of freedom and three RRRS kinematic chains. Here, R and S indicate revolute and spherical joints, respectively, and the first and third R joints of each chain are actuated. First, the paper presents an algorithm to find a closed-form solution to the inverse kinematic problem. The analysis shows there can be four different solutions for each kinematic chain. Next, the paper studies forward kinematics and develops an elimination-based approach to handle this problem. The proposed method relies on the vector convolution operation and avoids symbolic computations inherent to most other similar techniques. It is shown that the forward kinematics has up to 16 distinct solutions, corresponding to 16 different assembly modes of the mechanism. Numerical examples illustrate the developed techniques for both the inverse and forward kinematic problems. The proposed algorithms provide the basis for subsequent performance evaluation and design optimization, and they can be applied to other parallel mechanisms.
{"title":"Inverse and forward kinematic analysis of a 6-DOF foldable mechanism with a circular rail (FoldRail mechanism)","authors":"Anton Antonov, Alexey Fomin, Sergey Kiselev","doi":"10.1016/j.mechmachtheory.2024.105904","DOIUrl":"10.1016/j.mechmachtheory.2024.105904","url":null,"abstract":"<div><div>This article considers an inverse and forward kinematic analysis of a recently proposed foldable parallel mechanism with a circular rail (FoldRail mechanism). The mechanism has six degrees of freedom and three RRRS kinematic chains. Here, R and S indicate revolute and spherical joints, respectively, and the first and third R joints of each chain are actuated. First, the paper presents an algorithm to find a closed-form solution to the inverse kinematic problem. The analysis shows there can be four different solutions for each kinematic chain. Next, the paper studies forward kinematics and develops an elimination-based approach to handle this problem. The proposed method relies on the vector convolution operation and avoids symbolic computations inherent to most other similar techniques. It is shown that the forward kinematics has up to 16 distinct solutions, corresponding to 16 different assembly modes of the mechanism. Numerical examples illustrate the developed techniques for both the inverse and forward kinematic problems. The proposed algorithms provide the basis for subsequent performance evaluation and design optimization, and they can be applied to other parallel mechanisms.</div></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"206 ","pages":"Article 105904"},"PeriodicalIF":4.5,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143156094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-08DOI: 10.1016/j.mechmachtheory.2024.105902
Xianwen Kong
This paper deals with the type synthesis of variable-DOF (degree-of-freedom) single-loop spatial mechanisms — a class of reconfigurable mechanisms that DOF may change. A construction method is proposed to the type synthesis of variable-DOF single-loop mechanisms using Bennett 4R mechanisms and Goldberg 5R mechanisms. Using this approach, variable-DOF single-loop mechanisms can be obtained by first constructing multi-DOF multi-loop overconstrained mechanisms and then obtaining multi-DOF single-loop overconstrained mechanisms from these multi-DOF multi-loop mechanisms. Six types of variable-DOF single-loop 7R mechanisms and three types of variable-DOF single-loop 8R mechanisms have been obtained. No variable-DOF single-loop nR (n8) mechanisms can be constructed using Bennett 4R mechanisms and Goldberg 5R mechanisms. Isomeric variations of these variable-DOF mechanisms can be further obtained by isomerization. This work provides a solid foundation for further investigation on variable-DOF single-loop mechanisms.
{"title":"Type synthesis of variable-DOF single-loop spatial mechanisms using Bennett 4R mechanisms and Goldberg 5R mechanisms","authors":"Xianwen Kong","doi":"10.1016/j.mechmachtheory.2024.105902","DOIUrl":"10.1016/j.mechmachtheory.2024.105902","url":null,"abstract":"<div><div>This paper deals with the type synthesis of variable-DOF (degree-of-freedom) single-loop spatial mechanisms — a class of reconfigurable mechanisms that DOF may change. A construction method is proposed to the type synthesis of variable-DOF single-loop mechanisms using Bennett 4R mechanisms and Goldberg 5R mechanisms. Using this approach, variable-DOF single-loop mechanisms can be obtained by first constructing multi-DOF multi-loop overconstrained mechanisms and then obtaining multi-DOF single-loop overconstrained mechanisms from these multi-DOF multi-loop mechanisms. Six types of variable-DOF single-loop 7R mechanisms and three types of variable-DOF single-loop 8R mechanisms have been obtained. No variable-DOF single-loop nR (n<span><math><mo>></mo></math></span>8) mechanisms can be constructed using Bennett 4R mechanisms and Goldberg 5R mechanisms. Isomeric variations of these variable-DOF mechanisms can be further obtained by isomerization. This work provides a solid foundation for further investigation on variable-DOF single-loop mechanisms.</div></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"206 ","pages":"Article 105902"},"PeriodicalIF":4.5,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Deployable polygonal mechanisms (DGMs) are widely used in various fields; however, their performance evaluation remains challenging due to limitations in existing indices. To address these shortcomings, this paper innovatively proposes several new evaluation indices for DGMs, aiming to improve the precision and comprehensiveness of performance analysis. Firstly, a velocity analysis method for single-loop DGMs based on deployable paths is introduced, eliminating the need to solve joint angle analytical expressions, reducing computational effort. Secondly, a method for calculating the transmission wrench screw of single-loop mechanisms is proposed. This method is applicable to overconstrained, non-overconstrained, and reconfigurable mechanisms, regardless of whether they possess a single or multiple degrees of freedom. Thirdly, an index for evaluating the deploying performance of R DGMs that deploy into general planar polygons is developed, along with an algorithm for calculating folding length. Furthermore, novel evaluation indices for deployingfolding performance in various application scenarios, motionforce transmission performance, and transmission ratio stability are proposed. Finally, detailed analyses of deployingfolding performance, transmission ratio stability, global extreme velocity, global extreme stiffness, and motionforce transmission performance of R DGMs are provided.
{"title":"Kinematics and performance analysis for single-loop deployable polygonal mechanisms based on deployable paths","authors":"Hao Chen , Gaohan Zhu , Weizhong Guo , Zhenghao Weng , Caizhi Zhou , Mingxuan Wang","doi":"10.1016/j.mechmachtheory.2024.105907","DOIUrl":"10.1016/j.mechmachtheory.2024.105907","url":null,"abstract":"<div><div>Deployable polygonal mechanisms (DGMs) are widely used in various fields; however, their performance evaluation remains challenging due to limitations in existing indices. To address these shortcomings, this paper innovatively proposes several new evaluation indices for DGMs, aiming to improve the precision and comprehensiveness of performance analysis. Firstly, a velocity analysis method for single-loop DGMs based on deployable paths is introduced, eliminating the need to solve joint angle analytical expressions, reducing computational effort. Secondly, a method for calculating the transmission wrench screw of single-loop mechanisms is proposed. This method is applicable to overconstrained, non-overconstrained, and reconfigurable mechanisms, regardless of whether they possess a single or multiple degrees of freedom. Thirdly, an index for evaluating the deploying performance of <span><math><mi>n</mi></math></span>R DGMs that deploy into general planar polygons is developed, along with an algorithm for calculating folding length. Furthermore, novel evaluation indices for deploying<span><math><mo>/</mo></math></span>folding performance in various application scenarios, motion<span><math><mo>/</mo></math></span>force transmission performance, and transmission ratio stability are proposed. Finally, detailed analyses of deploying<span><math><mo>/</mo></math></span>folding performance, transmission ratio stability, global extreme velocity, global extreme stiffness, and motion<span><math><mo>/</mo></math></span>force transmission performance of <span><math><mi>n</mi></math></span>R DGMs are provided.</div></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"206 ","pages":"Article 105907"},"PeriodicalIF":4.5,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143156095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-06DOI: 10.1016/j.mechmachtheory.2024.105909
Zongxiang Yue , Zengcheng Wang , Zhaobo Chen , Jianjun Qu , Guangbin Yu , Jiazhi Wang , Shuai Mo
During the operation of herringbone gears some phenomena such as gear disengagement and back-side meshing (BSM) can lead to dynamic instability. Precise description of the behavior of multi-state meshing (MSM) is essential for the optimization of structures and for evaluation of its performance. In this article a nonlinear dynamic model for a herringbone gear is introduced. This model includes MSM and takes backlash and friction into account. MSM behavior is identified, and a dynamic stability rate (DSR) is calculated using various Poincaré maps. In addition, a number of bifurcation diagrams and phase diagrams are examined as well as the correlation between MSM characteristics and DSR. The study reveals that as the meshing frequency increases, the system transitions from stable periodic motion to complex periodic and chaotic responses before stabilizing into periodic motion. Transmission errors significantly influence MSM characteristics, with smaller errors making the DSR more sensitive to bifurcations and phase trajectory changes. Increased damping improves stability by suppressing BSM and chaotic motion. Under varying loads, the system transitions through different dynamic states, with periodic jumps notably affecting DSR at higher loads. Additionally, backlash plays a critical role in MSM behavior, influencing the transitions between periodic and chaotic responses. These findings highlight the importance of optimizing damping, load, and backlash to enhance the motion stability and performance of herringbone gear systems.
{"title":"Analysis of multi-state meshing and dynamic stability of herringbone gears considering friction based on nonlinear dynamics","authors":"Zongxiang Yue , Zengcheng Wang , Zhaobo Chen , Jianjun Qu , Guangbin Yu , Jiazhi Wang , Shuai Mo","doi":"10.1016/j.mechmachtheory.2024.105909","DOIUrl":"10.1016/j.mechmachtheory.2024.105909","url":null,"abstract":"<div><div>During the operation of herringbone gears some phenomena such as gear disengagement and back-side meshing (BSM) can lead to dynamic instability. Precise description of the behavior of multi-state meshing (MSM) is essential for the optimization of structures and for evaluation of its performance. In this article a nonlinear dynamic model for a herringbone gear is introduced. This model includes MSM and takes backlash and friction into account. MSM behavior is identified, and a dynamic stability rate (DSR) is calculated using various Poincaré maps. In addition, a number of bifurcation diagrams and phase diagrams are examined as well as the correlation between MSM characteristics and DSR. The study reveals that as the meshing frequency increases, the system transitions from stable periodic motion to complex periodic and chaotic responses before stabilizing into periodic motion. Transmission errors significantly influence MSM characteristics, with smaller errors making the DSR more sensitive to bifurcations and phase trajectory changes. Increased damping improves stability by suppressing BSM and chaotic motion. Under varying loads, the system transitions through different dynamic states, with periodic jumps notably affecting DSR at higher loads. Additionally, backlash plays a critical role in MSM behavior, influencing the transitions between periodic and chaotic responses. These findings highlight the importance of optimizing damping, load, and backlash to enhance the motion stability and performance of herringbone gear systems.</div></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"206 ","pages":"Article 105909"},"PeriodicalIF":4.5,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-04DOI: 10.1016/j.mechmachtheory.2024.105911
Guangxi Li , Haitao Liu , Qi Liu
High-order parametric continuity in toolpath generation and smooth passage through singular regions are paramount in five-axis machining. This paper introduces a generalized method for toolpath planning of a 5-DOF machining robot, which encompasses a two-pronged strategy: a toolpath smoothing technique and a singularity avoidance strategy. Initially, the control points of smoothing B-splines are analytically derived using curvature derivative continuity criteria for both linear and arc path segments. On this basis, an effective corner smoothing method, which is capable of addressing the line-line, line-arc, and arc-arc pairs, is developed for the tool position path, and a specialized approach similar to spatial arc-arc pair smoothing is employed for the tool orientation path. Subsequently, an analytical parameter synchronization technique is applied to generate a C3 continuous toolpath. A real-time singularity avoidance strategy is then proposed to improve the toolpath continuity near the singular configuration of the machining equipment. The effectiveness of the proposed method is verified through simulations and experiments on a robot machining platform, with the integration of a jerk-continuous feedrate profile. The findings indicate that the equipment can operate effectively throughout its entire workspace thanks to the proposed toolpath planning method.
{"title":"A generalized method for C3 continuous toolpath planning and its application in robot machining","authors":"Guangxi Li , Haitao Liu , Qi Liu","doi":"10.1016/j.mechmachtheory.2024.105911","DOIUrl":"10.1016/j.mechmachtheory.2024.105911","url":null,"abstract":"<div><div>High-order parametric continuity in toolpath generation and smooth passage through singular regions are paramount in five-axis machining. This paper introduces a generalized method for toolpath planning of a 5-DOF machining robot, which encompasses a two-pronged strategy: a toolpath smoothing technique and a singularity avoidance strategy. Initially, the control points of smoothing B-splines are analytically derived using curvature derivative continuity criteria for both linear and arc path segments. On this basis, an effective corner smoothing method, which is capable of addressing the line-line, line-arc, and arc-arc pairs, is developed for the tool position path, and a specialized approach similar to spatial arc-arc pair smoothing is employed for the tool orientation path. Subsequently, an analytical parameter synchronization technique is applied to generate a C<sup>3</sup> continuous toolpath. A real-time singularity avoidance strategy is then proposed to improve the toolpath continuity near the singular configuration of the machining equipment. The effectiveness of the proposed method is verified through simulations and experiments on a robot machining platform, with the integration of a jerk-continuous feedrate profile. The findings indicate that the equipment can operate effectively throughout its entire workspace thanks to the proposed toolpath planning method.</div></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"206 ","pages":"Article 105911"},"PeriodicalIF":4.5,"publicationDate":"2025-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-03DOI: 10.1016/j.mechmachtheory.2024.105898
Fengfeng Liu , Geng Liu , Lan Liu , Jingyi Gong
A recursive method is proposed for determining long-period time-varying mesh stiffness (TVMS) of cylindrical gears, considering real tooth surface deviations. Due to variations in the real deviations of each gear tooth and the presence of hunting tooth pairs, the superposition of contact point deviations between the driving and driven gears results in a long period for the TVMS. A long-period recursive model of contact point deviation superposition is developed based on even mesh technique and tooth surface measurement technique. This model considers the matching relationships of contact elements and the forward and backward recursion relationships of each contact element over a long period. Furthermore, a loaded tooth contact analysis (LTCA) model with long-period superposition deviations is established, and a double-layer iterative algorithm is devised to solve for long-period TVMS and transmission error (TE). The validity of the proposed method is confirmed through tooth surface measurements and TE experiments. The effects of load, deviation superposition, and deviation size on long-period TVMS are investigated. Finally, the main frequency components in the TVMS spectrum that may cause low-frequency vibrations in gears are identified.
{"title":"A recursive method for determining long-period mesh stiffness of cylindrical gears considering real tooth surface deviations","authors":"Fengfeng Liu , Geng Liu , Lan Liu , Jingyi Gong","doi":"10.1016/j.mechmachtheory.2024.105898","DOIUrl":"10.1016/j.mechmachtheory.2024.105898","url":null,"abstract":"<div><div>A recursive method is proposed for determining long-period time-varying mesh stiffness (TVMS) of cylindrical gears, considering real tooth surface deviations. Due to variations in the real deviations of each gear tooth and the presence of hunting tooth pairs, the superposition of contact point deviations between the driving and driven gears results in a long period for the TVMS. A long-period recursive model of contact point deviation superposition is developed based on even mesh technique and tooth surface measurement technique. This model considers the matching relationships of contact elements and the forward and backward recursion relationships of each contact element over a long period. Furthermore, a loaded tooth contact analysis (LTCA) model with long-period superposition deviations is established, and a double-layer iterative algorithm is devised to solve for long-period TVMS and transmission error (TE). The validity of the proposed method is confirmed through tooth surface measurements and TE experiments. The effects of load, deviation superposition, and deviation size on long-period TVMS are investigated. Finally, the main frequency components in the TVMS spectrum that may cause low-frequency vibrations in gears are identified.</div></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"206 ","pages":"Article 105898"},"PeriodicalIF":4.5,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143156091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work describes the kinematic properties achievable by using vanes with elliptical tip shapes in balanced vane pumps. The position of the contact point is analytically determined by taking advantage of the ellipse geometrical properties, which lead to a set of nonlinear algebraic and trigonometric equations. The kinematics is then linked to the main design parameters of the vane tip, allowing for the determination of the admissible domain of the vane geometry given the cam ring profile. A parametric study is then performed to highlight the potentials of this design solution, which gives additional parameters to control the pump design with respect to the classical circular tip vanes. The analysis involves also the tip eccentricity, a key parameter in the definition of the production tolerances, demonstrating the robustness of this design solution. Finally, performance indicators are defined to evaluate this aspect.
{"title":"Advantages of elliptical tip vanes on the kinematic design of balanced vane pumps","authors":"Caterina Natali, Mattia Battarra, Enrico Proner, Emiliano Mucchi","doi":"10.1016/j.mechmachtheory.2024.105901","DOIUrl":"10.1016/j.mechmachtheory.2024.105901","url":null,"abstract":"<div><div>This work describes the kinematic properties achievable by using vanes with elliptical tip shapes in balanced vane pumps. The position of the contact point is analytically determined by taking advantage of the ellipse geometrical properties, which lead to a set of nonlinear algebraic and trigonometric equations. The kinematics is then linked to the main design parameters of the vane tip, allowing for the determination of the admissible domain of the vane geometry given the cam ring profile. A parametric study is then performed to highlight the potentials of this design solution, which gives additional parameters to control the pump design with respect to the classical circular tip vanes. The analysis involves also the tip eccentricity, a key parameter in the definition of the production tolerances, demonstrating the robustness of this design solution. Finally, performance indicators are defined to evaluate this aspect.</div></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"206 ","pages":"Article 105901"},"PeriodicalIF":4.5,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143100777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-31DOI: 10.1016/j.mechmachtheory.2024.105897
Yang Zhang , Wenxuan Wang , Xi Kang , Bing Li
Deployable multi-closed-loop truss modules (MCLTMs) with a two-dimensional synchronous deployment motion, exhibit significant potential in constructing aerospace platforms due to their advantages of high stiffness and large deploying/folding ratio. This study addresses the kinematic and performance analysis of MCLTM and develops a prototype with optimized parameters. Firstly, the mobility and kinematic model of MCLTM are analyzed. Subsequently, three types of deploying/folding ratios for the modules are defined and analyzed. A stiffness analysis method for multi-closed-loop mechanisms is proposed. Utilizing the method, the stiffness model of the mechanism is established. Based on the stiffness model, stiffness performance indicators are defined and analyzed. The structure parameters of MCLTM are optimized based on the mapping curve between these performances and key design parameters. Finally, the prototype and the drive system are developed, and deployment and stiffness experiments are conducted to verify the feasibility of the mechanism and the correctness of kinematic and performance analyses. This work not only contributes to enriching and developing the theoretical system of deployable mechanisms but also provides a valuable reference for the prototype development of deployable mechanisms.
{"title":"Design, analysis, and experimentation of deployable multi-closed-loop truss modules for aerospace platforms","authors":"Yang Zhang , Wenxuan Wang , Xi Kang , Bing Li","doi":"10.1016/j.mechmachtheory.2024.105897","DOIUrl":"10.1016/j.mechmachtheory.2024.105897","url":null,"abstract":"<div><div>Deployable multi-closed-loop truss modules (MCLTMs) with a two-dimensional synchronous deployment motion, exhibit significant potential in constructing aerospace platforms due to their advantages of high stiffness and large deploying/folding ratio. This study addresses the kinematic and performance analysis of MCLTM and develops a prototype with optimized parameters. Firstly, the mobility and kinematic model of MCLTM are analyzed. Subsequently, three types of deploying/folding ratios for the modules are defined and analyzed. A stiffness analysis method for multi-closed-loop mechanisms is proposed. Utilizing the method, the stiffness model of the mechanism is established. Based on the stiffness model, stiffness performance indicators are defined and analyzed. The structure parameters of MCLTM are optimized based on the mapping curve between these performances and key design parameters. Finally, the prototype and the drive system are developed, and deployment and stiffness experiments are conducted to verify the feasibility of the mechanism and the correctness of kinematic and performance analyses. This work not only contributes to enriching and developing the theoretical system of deployable mechanisms but also provides a valuable reference for the prototype development of deployable mechanisms.</div></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"205 ","pages":"Article 105897"},"PeriodicalIF":4.5,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143166452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-30DOI: 10.1016/j.mechmachtheory.2024.105895
Qingxing Xi , Zhijun Chen , Ke Yin , Xu Liu , Feng Gao
The fault-tolerant gait for legged robots can improve the reliability and prolong the service time. However, few fault-tolerant gaits are available for hexapod robots with parallel leg mechanisms to realize the walkability and adapt to rough terrains when several active joints locked. This paper proposes a fault-tolerant gait for hexapod robots based on the non-fault gait without changing its gait sequence. First, a hexapod robot with serial-parallel leg mechanism is introduced. Then, the fault-tolerant gait with partial active joints locked based on typical walking gait is proposed. The gait planning algorithm selects the minimum square sum of the displacements of the active joints as the objective function to improve the walking ability of the robot. Further, two examples are chosen to analyze the walking ability on ground and rough terrain. Finally, experiments are carried out to validate the fault-tolerant gait and its performances. The results show that the fault-tolerant gait can effectively solve the walking of hexapod robots with partial active joints locked and it can also walk in different directions and traverse rough terrains such as steps.
{"title":"Fault-tolerant gait for Hexapod Robots with partial active joints locked","authors":"Qingxing Xi , Zhijun Chen , Ke Yin , Xu Liu , Feng Gao","doi":"10.1016/j.mechmachtheory.2024.105895","DOIUrl":"10.1016/j.mechmachtheory.2024.105895","url":null,"abstract":"<div><div>The fault-tolerant gait for legged robots can improve the reliability and prolong the service time. However, few fault-tolerant gaits are available for hexapod robots with parallel leg mechanisms to realize the walkability and adapt to rough terrains when several active joints locked. This paper proposes a fault-tolerant gait for hexapod robots based on the non-fault gait without changing its gait sequence. First, a hexapod robot with serial-parallel leg mechanism is introduced. Then, the fault-tolerant gait with partial active joints locked based on typical walking gait is proposed. The gait planning algorithm selects the minimum square sum of the displacements of the active joints as the objective function to improve the walking ability of the robot. Further, two examples are chosen to analyze the walking ability on ground and rough terrain. Finally, experiments are carried out to validate the fault-tolerant gait and its performances. The results show that the fault-tolerant gait can effectively solve the walking of hexapod robots with partial active joints locked and it can also walk in different directions and traverse rough terrains such as steps.</div></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"205 ","pages":"Article 105895"},"PeriodicalIF":4.5,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143166451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-30DOI: 10.1016/j.mechmachtheory.2024.105893
Qizhi Meng , Marco Ceccarelli
With the increasing magnitude and complexity of space missions, coupled with higher energy collection and stronger signal transmission demands, support trusses of solar panels and antennas are evolving towards larger scales. Similar to assembling elements, the cellular mechanisms are crucial for achieving large-scale space structures. Following this concept, this paper focuses on type synthesis and structure screening of deployable cellular mechanisms. Considering the heightened reliability of revolute joints, the target mechanism exclusively incorporates such joints. First, a graphical-type synthesis method is introduced to synthesize deployable cellular mechanisms. Serialized deployable cellular mechanisms are designed utilizing the 2Pa (Pa: parallelogram mechanism) and 4R (R: revolute joint) kinematic chains as backbone mechanisms. Subsequently, structure screening of deployable cellular mechanisms is carried out by motion-force interaction performance analysis with the power coefficient as a criterion. Then workspaces with different motion-force interaction performances are identified for the selected deployable cellular mechanisms. Prototype construction and test show that the proposed mechanisms achieve one-degree-of-freedom deployable movement. The proposed deployable cellular mechanisms are expected to play significant roles in constructing deployable modules.
{"title":"Type synthesis and structure screening of deployable cellular mechanisms based on the graphical method and motion-force interaction performance","authors":"Qizhi Meng , Marco Ceccarelli","doi":"10.1016/j.mechmachtheory.2024.105893","DOIUrl":"10.1016/j.mechmachtheory.2024.105893","url":null,"abstract":"<div><div>With the increasing magnitude and complexity of space missions, coupled with higher energy collection and stronger signal transmission demands, support trusses of solar panels and antennas are evolving towards larger scales. Similar to assembling elements, the cellular mechanisms are crucial for achieving large-scale space structures. Following this concept, this paper focuses on type synthesis and structure screening of deployable cellular mechanisms. Considering the heightened reliability of revolute joints, the target mechanism exclusively incorporates such joints. First, a graphical-type synthesis method is introduced to synthesize deployable cellular mechanisms. Serialized deployable cellular mechanisms are designed utilizing the 2Pa (Pa: parallelogram mechanism) and 4R (R: revolute joint) kinematic chains as backbone mechanisms. Subsequently, structure screening of deployable cellular mechanisms is carried out by motion-force interaction performance analysis with the power coefficient as a criterion. Then workspaces with different motion-force interaction performances are identified for the selected deployable cellular mechanisms. Prototype construction and test show that the proposed mechanisms achieve one-degree-of-freedom deployable movement. The proposed deployable cellular mechanisms are expected to play significant roles in constructing deployable modules.</div></div>","PeriodicalId":49845,"journal":{"name":"Mechanism and Machine Theory","volume":"205 ","pages":"Article 105893"},"PeriodicalIF":4.5,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143166453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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