Programmable mechanical structures are formed by autonomous and adaptive cells and can reproduce meshes known from the finite element method. Furthermore, they can change their structure not only through morphing, but also by self-reconfiguration of the cells. A crucial component of the cells, which can preserve the underlying geometry of a triangular mesh, are six-bar linkages. The main part of the present contribution concerns the six-bar linkages as a fully 3D-printable compliant mechanism where each revolute joint of the six-bar linkage is replaced with a notch flexure hinge with circular contour. There are two key drawbacks associated with the use of notch flexure hinges, namely, compliance in the flexure hinges and the fact that the center of rotation is not maintained. For self-reconfiguration of the cells, an efficient model is needed to predict the positioning errors. Therefore, the flexure hinge is represented by three distinct models, namely a finite element model, a beam model, and a simplified linearized model based on translational and rotational spring elements. These models are compared and evaluated in succession first to identify the parameters of the simplified model and later on, the simplified model is used to show the deviations of a medium-scaled programmable structure with respect to the idealized behavior. The current work brings us closer to both the development of programmable mechanical structures and the prediction of positioning errors during self-reconfiguration.
{"title":"Six-bar Linkages with Compliant Mechanisms for Programmable Mechanical Structures","authors":"M. Pieber, J. Gerstmayr","doi":"10.1115/1.4063168","DOIUrl":"https://doi.org/10.1115/1.4063168","url":null,"abstract":"\u0000 Programmable mechanical structures are formed by autonomous and adaptive cells and can reproduce meshes known from the finite element method. Furthermore, they can change their structure not only through morphing, but also by self-reconfiguration of the cells. A crucial component of the cells, which can preserve the underlying geometry of a triangular mesh, are six-bar linkages. The main part of the present contribution concerns the six-bar linkages as a fully 3D-printable compliant mechanism where each revolute joint of the six-bar linkage is replaced with a notch flexure hinge with circular contour. There are two key drawbacks associated with the use of notch flexure hinges, namely, compliance in the flexure hinges and the fact that the center of rotation is not maintained. For self-reconfiguration of the cells, an efficient model is needed to predict the positioning errors. Therefore, the flexure hinge is represented by three distinct models, namely a finite element model, a beam model, and a simplified linearized model based on translational and rotational spring elements. These models are compared and evaluated in succession first to identify the parameters of the simplified model and later on, the simplified model is used to show the deviations of a medium-scaled programmable structure with respect to the idealized behavior. The current work brings us closer to both the development of programmable mechanical structures and the prediction of positioning errors during self-reconfiguration.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45074088","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}
M. Clancy, Fayez Alruwaili, Marzieh S. Saeedi-Hosseiny, Sean McMillan, Ioan Iulian Iordachita, Mohammad H. Abedin-Nasab
Robot-assisted femur repair has been of increased interest in recent literature due to the success of robot-assisted surgeries and current reoperation rates for femur fracture surgeries. The current limitation of robot-assisted femur fracture surgery is the lack of large force generation and sufficient workspace size in traditional mechanisms. To address these challenges, our group has created a 3-RRPS parallel mechanism, Robossis, which maintains the strength of parallel mechanisms while improving the translational and rotational workspace volume. In this paper, an optimal design methodology of parallel mechanisms for application to robot-assisted femur fracture surgery using a single-objective genetic algorithm is proposed. The genetic algorithm will use a single objective function to evaluate the various configurations based on the clinical and mechanical design criteria for femur fracture surgery as well as the global conditioning index. The objective function is composed of the desired translational and rotational workspaces based on the design criteria, the dynamic load-carrying capacity, and the homogenous-Jacobian global conditioning index. Lastly, experimental results of Robossis were obtained to validate the kinematic solution and the mechanism itself; Robossis had an average error of 0.31mm during experimental force testing.
{"title":"Analysis and Optimization of a 6-DoF 3-RRPS Parallel Mechanism for Robot-Assisted Long-Bone Fracture Surgery","authors":"M. Clancy, Fayez Alruwaili, Marzieh S. Saeedi-Hosseiny, Sean McMillan, Ioan Iulian Iordachita, Mohammad H. Abedin-Nasab","doi":"10.1115/1.4063167","DOIUrl":"https://doi.org/10.1115/1.4063167","url":null,"abstract":"\u0000 Robot-assisted femur repair has been of increased interest in recent literature due to the success of robot-assisted surgeries and current reoperation rates for femur fracture surgeries. The current limitation of robot-assisted femur fracture surgery is the lack of large force generation and sufficient workspace size in traditional mechanisms. To address these challenges, our group has created a 3-RRPS parallel mechanism, Robossis, which maintains the strength of parallel mechanisms while improving the translational and rotational workspace volume. In this paper, an optimal design methodology of parallel mechanisms for application to robot-assisted femur fracture surgery using a single-objective genetic algorithm is proposed. The genetic algorithm will use a single objective function to evaluate the various configurations based on the clinical and mechanical design criteria for femur fracture surgery as well as the global conditioning index. The objective function is composed of the desired translational and rotational workspaces based on the design criteria, the dynamic load-carrying capacity, and the homogenous-Jacobian global conditioning index. Lastly, experimental results of Robossis were obtained to validate the kinematic solution and the mechanism itself; Robossis had an average error of 0.31mm during experimental force testing.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47859964","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}
The unique structural characteristics of hybrid robots, such as few-DOF and redundant constraints, lead to a series of challenges in the establishment of theoretical models. However, these theoretical models are indispensable parts of motion control. Therefore, this paper focus on establishing the kinematics, dynamics and stiffness models for an Exechon-like hybrid robot, which are then used for error compensation and velocity planning to improve the robot motion performance. Firstly, the kinematic model is derived through intermediate parameters and the kinematics equivalent chains. By analyzing the parasitic motion due to few-DOF, the redundant equations in the model are eliminated to obtain the solution of inverse kinematics. Secondly, based on the beam element, the optimal equivalent configuration of the moving platform which connects the parallel part and serial part is determined and then an entire equivalent structure of the robot is formed. It helps establish the stiffness model by using the Matrix Structure Analysis method. Next, the dynamic model is established by combining the Newton Euler method with co-deformation theory to solve the underdetermined dynamic equations caused by redundant constraints. Finally, the compensation method is designed based on the stiffness model and kinematic model to improve the end positioning accuracy of the robot; the velocity planning algorithm is designed based on the dynamic model and kinematic model to enhance the smoothness of the robot motion. The methods proposed in this paper are also of referential significance to other Exechon-like hybrid robots.
{"title":"Motion Performance Study of 2UPR-1RPS/2R Hybrid Robot based on Kinematics, Dynamics and Stiffness Modeling","authors":"Jing Li, Ninghe Lu, Nanyan Shen, Zehui Ma, Ziqi Zhao","doi":"10.1115/1.4063169","DOIUrl":"https://doi.org/10.1115/1.4063169","url":null,"abstract":"\u0000 The unique structural characteristics of hybrid robots, such as few-DOF and redundant constraints, lead to a series of challenges in the establishment of theoretical models. However, these theoretical models are indispensable parts of motion control. Therefore, this paper focus on establishing the kinematics, dynamics and stiffness models for an Exechon-like hybrid robot, which are then used for error compensation and velocity planning to improve the robot motion performance. Firstly, the kinematic model is derived through intermediate parameters and the kinematics equivalent chains. By analyzing the parasitic motion due to few-DOF, the redundant equations in the model are eliminated to obtain the solution of inverse kinematics. Secondly, based on the beam element, the optimal equivalent configuration of the moving platform which connects the parallel part and serial part is determined and then an entire equivalent structure of the robot is formed. It helps establish the stiffness model by using the Matrix Structure Analysis method. Next, the dynamic model is established by combining the Newton Euler method with co-deformation theory to solve the underdetermined dynamic equations caused by redundant constraints. Finally, the compensation method is designed based on the stiffness model and kinematic model to improve the end positioning accuracy of the robot; the velocity planning algorithm is designed based on the dynamic model and kinematic model to enhance the smoothness of the robot motion. The methods proposed in this paper are also of referential significance to other Exechon-like hybrid robots.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42451560","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}
Sajeeva Abeywardena, Eisa Anwar, S. Miller, I. Farkhatdinov
Humans are intrinsically unstable in quiet stance from a rigid body system viewpoint; however, they maintain balance thanks to neuro-muscular sensory control properties. With increasing levels of balance related incidents in industrial and ageing populations globally each year, the development of assistive mechanisms to augment human balance is paramount. This work investigates the mechanical characteristics of kinematically dissimilar one and two degrees-of-freedom supernumerary robotic tails for balance augmentation. Through dynamic simulations and manipulability assessments, the importance of variable coupling inertia in creating a sufficient reaction torque is highlighted. It is shown that two-dof tails with solely revolute joints are best suited to address the balance augmentation issue. Within the two-dof options, the characteristics of open versus closed loop tails is investigated, with the ultimate design selection requiring trade-offs between environmental workspace, biomechanical factors and manufacturing ease to be made.
{"title":"Mechanical characterisation of supernumerary robotic tails for human balance augmentation","authors":"Sajeeva Abeywardena, Eisa Anwar, S. Miller, I. Farkhatdinov","doi":"10.1115/1.4063094","DOIUrl":"https://doi.org/10.1115/1.4063094","url":null,"abstract":"\u0000 Humans are intrinsically unstable in quiet stance from a rigid body system viewpoint; however, they maintain balance thanks to neuro-muscular sensory control properties. With increasing levels of balance related incidents in industrial and ageing populations globally each year, the development of assistive mechanisms to augment human balance is paramount. This work investigates the mechanical characteristics of kinematically dissimilar one and two degrees-of-freedom supernumerary robotic tails for balance augmentation. Through dynamic simulations and manipulability assessments, the importance of variable coupling inertia in creating a sufficient reaction torque is highlighted. It is shown that two-dof tails with solely revolute joints are best suited to address the balance augmentation issue. Within the two-dof options, the characteristics of open versus closed loop tails is investigated, with the ultimate design selection requiring trade-offs between environmental workspace, biomechanical factors and manufacturing ease to be made.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44485156","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}
Ting Zou, Xinyu Jian, M. Al-Tamimi, Xing Wu, Jing Wu
This paper investigates the methodology and techniques for a soft biomimetic robot fish that has a straightforward design, relatively simple fabrication, and low cost. In addition to the investigations of fabrication techniques, we also explore the numerical analysis of the biological fish swimming performance, with its inspiration for robot fish design, which is less studied in the literature. In this research, therefore, various swimming locomotion patterns within the BCF (body and/or caudal fin) family are analyzed for kinematics & hydrodynamics using analytical methods and CFD (computational fluid dynamics) to inspire the robot fish design for improved swimming performance. Via straightforward design and fabrication, the swimming performance of the numerical robot fish is verified by means of simulation using 3D CFD and the prototype performance is validated using in-water experimental tests. This study showcases a new easy-to-design and easy-to-fabricate robust biomimetic robot fish with comparable swimming performance, which has good potential for purposes like education, research, and entertainment.
{"title":"Development of a Low-cost Soft Robot Fish with Biomimetic Swimming Performance","authors":"Ting Zou, Xinyu Jian, M. Al-Tamimi, Xing Wu, Jing Wu","doi":"10.1115/1.4063037","DOIUrl":"https://doi.org/10.1115/1.4063037","url":null,"abstract":"\u0000 This paper investigates the methodology and techniques for a soft biomimetic robot fish that has a straightforward design, relatively simple fabrication, and low cost. In addition to the investigations of fabrication techniques, we also explore the numerical analysis of the biological fish swimming performance, with its inspiration for robot fish design, which is less studied in the literature. In this research, therefore, various swimming locomotion patterns within the BCF (body and/or caudal fin) family are analyzed for kinematics & hydrodynamics using analytical methods and CFD (computational fluid dynamics) to inspire the robot fish design for improved swimming performance. Via straightforward design and fabrication, the swimming performance of the numerical robot fish is verified by means of simulation using 3D CFD and the prototype performance is validated using in-water experimental tests. This study showcases a new easy-to-design and easy-to-fabricate robust biomimetic robot fish with comparable swimming performance, which has good potential for purposes like education, research, and entertainment.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43280625","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}
An inverse kinematic mapping for redundant serial manipulators is presented at the configuration level, for which periodic manipulator operational trajectories map into periodic input trajectories; i.e., for which all serial manipulators are cyclic. The inverse mapping defines a differentiable manifold on which output and self-motion coordinates comprise operational coordinates that represent manipulator redundant degrees of freedom. The inverse mapping and differentiable manifold are defined in analytical form and a computational method for their evaluation is presented. Numerical examples are presented to illustrate validity of the formulation.
{"title":"A Cyclic Differentiable Manifold Representation of Redundant Manipulator Kinematics","authors":"E. Haug","doi":"10.1115/1.4063038","DOIUrl":"https://doi.org/10.1115/1.4063038","url":null,"abstract":"\u0000 An inverse kinematic mapping for redundant serial manipulators is presented at the configuration level, for which periodic manipulator operational trajectories map into periodic input trajectories; i.e., for which all serial manipulators are cyclic. The inverse mapping defines a differentiable manifold on which output and self-motion coordinates comprise operational coordinates that represent manipulator redundant degrees of freedom. The inverse mapping and differentiable manifold are defined in analytical form and a computational method for their evaluation is presented. Numerical examples are presented to illustrate validity of the formulation.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48363180","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}
Bi-stable structures have been widely utilized in soft grippers to reduce the energy required for maintaining grip. Grippers have been investigated in terms of the energy efficiency and accuracy of gripping; however, the limited number of gripping states hinders the holding of objects of various shapes. In this study, an energy-efficient gripper was developed to accommodate both convex and concave shapes using a tristable structure that combines two bistable structures, with shape memory alloy wires used as actuators. Different gripping modes were designed for convex and concave shapes, based on three states of the gripper: gripping, open, and holding. The gripper consisted of a driving part with a leaf spring for a “linear snap action”, and a soft finger part with an elastic ring and pre-stressed fingers. Geometric variables were adjusted to construct a tristable energy curve through experiments and analyses. The fabricated gripper weighed about 140 g and was capable of gripping convex objects of up to 80 g, and concave objects of about 120 g. Only a small amount of energy was consumed in the switching states, and the gripper maintained a stable state while gripping with no energy consumption. It is expected that this research will contribute to lightweight and energy-efficient grippers for application to drones, for example.
{"title":"Energy-efficient tristable soft gripper using shape memory alloy wires for gripping convex and concave objects","authors":"Seon Mi Jo, H. Yoon","doi":"10.1115/1.4062983","DOIUrl":"https://doi.org/10.1115/1.4062983","url":null,"abstract":"Bi-stable structures have been widely utilized in soft grippers to reduce the energy required for maintaining grip. Grippers have been investigated in terms of the energy efficiency and accuracy of gripping; however, the limited number of gripping states hinders the holding of objects of various shapes. In this study, an energy-efficient gripper was developed to accommodate both convex and concave shapes using a tristable structure that combines two bistable structures, with shape memory alloy wires used as actuators. Different gripping modes were designed for convex and concave shapes, based on three states of the gripper: gripping, open, and holding. The gripper consisted of a driving part with a leaf spring for a “linear snap action”, and a soft finger part with an elastic ring and pre-stressed fingers. Geometric variables were adjusted to construct a tristable energy curve through experiments and analyses. The fabricated gripper weighed about 140 g and was capable of gripping convex objects of up to 80 g, and concave objects of about 120 g. Only a small amount of energy was consumed in the switching states, and the gripper maintained a stable state while gripping with no energy consumption. It is expected that this research will contribute to lightweight and energy-efficient grippers for application to drones, for example.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47607115","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}
Xueyuan Gao, Fujuan Li, Xueyan Han, Xinwang Liu, Shihua Li
In order to obtain more configurations of multi-mode parallel mechanism with the expected motion modes, a new configuration synthesis method of multi-mode parallel mechanism is proposed in this paper. The generation principle of parallel mechanism with multiple motion modes is analyzed. The relation between the motion of moving platform and the motion of branch is obtained. The finite motion and instantaneous motion of existing variable mobility branches are analyzed, and variable mobility branches are decomposed into variable mobility generators. By using variable mobility generators to construct variable mobility branches, a configuration synthesis method of multi-mode parallel mechanism based on variable mobility branch is proposed. Taking the multi-mode parallel mechanism with 2T1R and 2R1T motion modes as an example, a new class of multi-mode parallel mechanisms are obtained. The proposed method enriches the configuration synthesis theory of multi-mode parallel mechanism and the synthesis results enrich the configurations of multi-mode parallel mechanism.
{"title":"Configuration Synthesis Method of Multi-Mode Parallel Mechanism Based on Variable Mobility Branch","authors":"Xueyuan Gao, Fujuan Li, Xueyan Han, Xinwang Liu, Shihua Li","doi":"10.1115/1.4062986","DOIUrl":"https://doi.org/10.1115/1.4062986","url":null,"abstract":"\u0000 In order to obtain more configurations of multi-mode parallel mechanism with the expected motion modes, a new configuration synthesis method of multi-mode parallel mechanism is proposed in this paper. The generation principle of parallel mechanism with multiple motion modes is analyzed. The relation between the motion of moving platform and the motion of branch is obtained. The finite motion and instantaneous motion of existing variable mobility branches are analyzed, and variable mobility branches are decomposed into variable mobility generators. By using variable mobility generators to construct variable mobility branches, a configuration synthesis method of multi-mode parallel mechanism based on variable mobility branch is proposed. Taking the multi-mode parallel mechanism with 2T1R and 2R1T motion modes as an example, a new class of multi-mode parallel mechanisms are obtained. The proposed method enriches the configuration synthesis theory of multi-mode parallel mechanism and the synthesis results enrich the configurations of multi-mode parallel mechanism.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48199077","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}
Peng Yan, Hailin Huang, Sen Wang, Bing Li, Zhifeng Zhang
Pipeline inspection in unknown environments is challenging for robots, and various In-pipe crawling robots have been developed in recent years to perform pipeline inspection. Most of these robots comprise multiple segments and require multiple actuators to realize the pipeline locomotion, resulting in complicated system composition and large energy consumption. In this paper, inspired by the crawling principles of earthworm locomotion, we propose a single-actuated camshaft robot that can realize multiple sequential motions for pipeline crawling. The proposed singled-actuated camshaft robot contains one actuator and three segments: head anchoring, body elongation, and rear anchoring segment. The multiple sequential motions of these three segments are realized based on the cam mechanisms. Umbrella-shaped elastic rubbers are longitudinally arranged around the head and rear anchoring segments. Each segment contains a cam bracket. The camshaft's rotatory motion pushes the cam brackets to generate the axial translational motion, resulting in the umbrella-shaped elastic rubbers being expanded or contracted. The proposed camshaft robot's expansion and contraction motion are sequentially realized by the phase deviation of the camshafts. First, the structures of the proposed robot are designed. Then, the cam curves are modeled, the expansion/contraction ratio of the rear/head anchoring segment is calculated, the phase deviation of the camshafts is determined, and multiple sequential motions of the proposed robot are simulated. Finally, we fabricate the proposed camshaft robot and carry out crawling experiments in pipelines with different shapes and diameters.
{"title":"Single-actuated camshaft robot with multiple sequential motions","authors":"Peng Yan, Hailin Huang, Sen Wang, Bing Li, Zhifeng Zhang","doi":"10.1115/1.4062987","DOIUrl":"https://doi.org/10.1115/1.4062987","url":null,"abstract":"\u0000 Pipeline inspection in unknown environments is challenging for robots, and various In-pipe crawling robots have been developed in recent years to perform pipeline inspection. Most of these robots comprise multiple segments and require multiple actuators to realize the pipeline locomotion, resulting in complicated system composition and large energy consumption. In this paper, inspired by the crawling principles of earthworm locomotion, we propose a single-actuated camshaft robot that can realize multiple sequential motions for pipeline crawling. The proposed singled-actuated camshaft robot contains one actuator and three segments: head anchoring, body elongation, and rear anchoring segment. The multiple sequential motions of these three segments are realized based on the cam mechanisms. Umbrella-shaped elastic rubbers are longitudinally arranged around the head and rear anchoring segments. Each segment contains a cam bracket. The camshaft's rotatory motion pushes the cam brackets to generate the axial translational motion, resulting in the umbrella-shaped elastic rubbers being expanded or contracted. The proposed camshaft robot's expansion and contraction motion are sequentially realized by the phase deviation of the camshafts. First, the structures of the proposed robot are designed. Then, the cam curves are modeled, the expansion/contraction ratio of the rear/head anchoring segment is calculated, the phase deviation of the camshafts is determined, and multiple sequential motions of the proposed robot are simulated. Finally, we fabricate the proposed camshaft robot and carry out crawling experiments in pipelines with different shapes and diameters.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43176809","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}
Trajectory learning is an important part of robot skill learning, and a trajectory learning method based on improved Dynamic Movement Primitives (DMPs) is proposed to improve trajectory reproduction accuracy. In this method, the truncation processing is used to improve the Gaussian kernel function of DMPs to eliminate the impact of tail exponential decay on fitted target forcing term, and the optimization on the number of shape parameters is used to make the model better approximate the local gradient of the target forcing term. The principle of trajectory accuracy improvement is described in detail. The trajectory reproduction simulation is performed, which verifies the feasibility of the proposed method. An experimental setup for robot skill trajectory learning is constructed and the relevant comparison experiments are performed, which verifies the effectiveness of the proposed method in improving trajectory learning accuracy.
{"title":"High Precision Trajectory Learning Method based Improved Dynamic Movement Primitives for Robot Skill Learning","authors":"Bin Zhai, Enzheng Zhang, Bingchen Li, Xiujun Fang","doi":"10.1115/1.4062985","DOIUrl":"https://doi.org/10.1115/1.4062985","url":null,"abstract":"\u0000 Trajectory learning is an important part of robot skill learning, and a trajectory learning method based on improved Dynamic Movement Primitives (DMPs) is proposed to improve trajectory reproduction accuracy. In this method, the truncation processing is used to improve the Gaussian kernel function of DMPs to eliminate the impact of tail exponential decay on fitted target forcing term, and the optimization on the number of shape parameters is used to make the model better approximate the local gradient of the target forcing term. The principle of trajectory accuracy improvement is described in detail. The trajectory reproduction simulation is performed, which verifies the feasibility of the proposed method. An experimental setup for robot skill trajectory learning is constructed and the relevant comparison experiments are performed, which verifies the effectiveness of the proposed method in improving trajectory learning accuracy.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44984302","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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