N. Robson, Vanessa Audrey, Ashutosh Dwivedi, Dylan Kunzmann
This paper explores the kinematic synthesis, design and pilot experimental testing of a six-legged walking robotic platform able to traverse through different terrains. We aim to develop a structured approach to designing the limb morphology using a relaxed kinematic task with incorporated conditions on foot-environments contact force direction (related to stability) and curvature constraints (related to maintaining contact). The design approach builds up incrementally starting with studying the basic human leg walking trajectory and then defining a “relaxed” kinematic task. The “relaxed” kinematic task consists only of two contact locations (toe-off and heel-strike) with higher order motion task specifications compatible with foot-terrain(s) contact and curvature constraints in the vicinity of the two contacts. As the next step, an eight-bar leg image is created based on the “relaxed” kinematic task and incorporated within a six-legged walking robot. Pilot experimental tests explore if the proposed approach results in an adaptable behavior which allows the platform to incorporate different walking foot trajectories and gait styles coupled to each environment. The results suggest that the proposed “relaxed” higher order motion task combined with the leg morphological properties and feet material allowed the platform to walk stably on the different terrains. The main advantage of the proposed method is that the platform has carefully designed limb morphology with incorporated conditions on foot-environment interaction and incorporates a single actuator to drive all six legs.
{"title":"Robust Multi-Legged Walking Robots for Interactions with Different Terrains","authors":"N. Robson, Vanessa Audrey, Ashutosh Dwivedi, Dylan Kunzmann","doi":"10.1115/1.4062303","DOIUrl":"https://doi.org/10.1115/1.4062303","url":null,"abstract":"\u0000 This paper explores the kinematic synthesis, design and pilot experimental testing of a six-legged walking robotic platform able to traverse through different terrains. We aim to develop a structured approach to designing the limb morphology using a relaxed kinematic task with incorporated conditions on foot-environments contact force direction (related to stability) and curvature constraints (related to maintaining contact). The design approach builds up incrementally starting with studying the basic human leg walking trajectory and then defining a “relaxed” kinematic task. The “relaxed” kinematic task consists only of two contact locations (toe-off and heel-strike) with higher order motion task specifications compatible with foot-terrain(s) contact and curvature constraints in the vicinity of the two contacts. As the next step, an eight-bar leg image is created based on the “relaxed” kinematic task and incorporated within a six-legged walking robot. Pilot experimental tests explore if the proposed approach results in an adaptable behavior which allows the platform to incorporate different walking foot trajectories and gait styles coupled to each environment. The results suggest that the proposed “relaxed” higher order motion task combined with the leg morphological properties and feet material allowed the platform to walk stably on the different terrains. The main advantage of the proposed method is that the platform has carefully designed limb morphology with incorporated conditions on foot-environment interaction and incorporates a single actuator to drive all six legs.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44636097","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}
Vimalesh Muralidharan, Nicolas Testard, C. Chevallereau, A. Abourachid, P. Wenger
This paper discusses stiffness and antagonistic actuation in light-weight cable-driven bio-inspired manipulators suitable for safe interactions. Manipulators under study are built upon arranging in series several tensegrity joints, called modules. A comparative study of several modules revealed that the X module, in contrast to modules based on pivots, allows one to increase joint stiffness by increasing antagonistic input forces like during muscle coactivation. For a planar manipulator with N modules, antagonistic actuation schemes with 2N and N+1 cables are proposed and compared. It is shown that the N+1 cable actuation scheme allows controlling both the manipulator configuration and joint stiffness satisfactorily. As compared with a manipulator with 2N active cables, one on each side of each module, higher forces are required to achieve the manipulator configuration. However, the N+1 cable actuation scheme is a reasonable solution that allows reducing moving masses and cost while offering more flexibility.
{"title":"Variable stiffness and antagonist actuation for cable-driven manipulators inspired by the bird neck","authors":"Vimalesh Muralidharan, Nicolas Testard, C. Chevallereau, A. Abourachid, P. Wenger","doi":"10.1115/1.4062302","DOIUrl":"https://doi.org/10.1115/1.4062302","url":null,"abstract":"\u0000 This paper discusses stiffness and antagonistic actuation in light-weight cable-driven bio-inspired manipulators suitable for safe interactions. Manipulators under study are built upon arranging in series several tensegrity joints, called modules. A comparative study of several modules revealed that the X module, in contrast to modules based on pivots, allows one to increase joint stiffness by increasing antagonistic input forces like during muscle coactivation. For a planar manipulator with N modules, antagonistic actuation schemes with 2N and N+1 cables are proposed and compared. It is shown that the N+1 cable actuation scheme allows controlling both the manipulator configuration and joint stiffness satisfactorily. As compared with a manipulator with 2N active cables, one on each side of each module, higher forces are required to achieve the manipulator configuration. However, the N+1 cable actuation scheme is a reasonable solution that allows reducing moving masses and cost while offering more flexibility.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45475655","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}
Redundantly actuated parallel manipulators with two rotations and one translation (2R1T RAPMs) have the potential for machining complex surfaces, where a large orientation workspace and high stiffness are required. Considering the advantages of an offset moving platform, such as enlarged orientation workspace and improved stiffness, a novel 2R1T (2PRR)R-PRS-PSS RAPM with an offset moving platform is proposed in this paper, called M2. Compared with the existing 2R1T RAPM with an offset moving platform, the main advantage of the proposed RAPM is that the heavy motors of four limbs are mounted on the base to reduce the movable mass and improve dynamic response. The kinematical analysis is investigated, including mobility, inverse, forward kinematics, and singularity analysis. Meanwhile, comprehensive evaluations of the properties of the offset moving platform and actuation redundancy are carried out. Compared with M2 RAPM's form without an offset in moving platform, i.e., no auxiliary platform, and M2 RAPM's nonredundantly actuated form, the proposed M2 RAPM can achieve a larger orientation workspace and higher stiffness. Particularly, the maximum stiffness of the proposed M2 is 68.8% larger than its form without an auxiliary platform. Finally, the dimensional parameters of the proposed M2 are optimized to obtain an improved satisfactory workspace.
{"title":"A 2R1T redundantly actuated parallel manipulator with an offset moving platform and fixed linear actuators","authors":"Ziying Lin, Lingmin Xu, Ye Ding, Xiang-Yang Zhu","doi":"10.1115/1.4062304","DOIUrl":"https://doi.org/10.1115/1.4062304","url":null,"abstract":"\u0000 Redundantly actuated parallel manipulators with two rotations and one translation (2R1T RAPMs) have the potential for machining complex surfaces, where a large orientation workspace and high stiffness are required. Considering the advantages of an offset moving platform, such as enlarged orientation workspace and improved stiffness, a novel 2R1T (2PRR)R-PRS-PSS RAPM with an offset moving platform is proposed in this paper, called M2. Compared with the existing 2R1T RAPM with an offset moving platform, the main advantage of the proposed RAPM is that the heavy motors of four limbs are mounted on the base to reduce the movable mass and improve dynamic response. The kinematical analysis is investigated, including mobility, inverse, forward kinematics, and singularity analysis. Meanwhile, comprehensive evaluations of the properties of the offset moving platform and actuation redundancy are carried out. Compared with M2 RAPM's form without an offset in moving platform, i.e., no auxiliary platform, and M2 RAPM's nonredundantly actuated form, the proposed M2 RAPM can achieve a larger orientation workspace and higher stiffness. Particularly, the maximum stiffness of the proposed M2 is 68.8% larger than its form without an auxiliary platform. Finally, the dimensional parameters of the proposed M2 are optimized to obtain an improved satisfactory workspace.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49403399","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}
In recent years, as robots are frequently required to interact with the external environment, the demand for robot joint flexibility has been increasing. Series elastic actuators (SEAs) are widely used in robot joints as typical compliant actuators. However, the stiffness model based on the classical beam theory has a large error with the reality, which raises the design difficulty. In this paper, the data obtained from finite element analysis is analyzed theoretically. A theoretical model of the stiffness of a typical symmetric elastic element is obtained. The design experiments are verified and the fitting accuracy is 98.27%, which is significantly higher than that of the stiffness model based on classical beam theory. It can be used to design elastic elements that meet specific stiffness requirements.
{"title":"Design and validation of symmetrical elastic elements in series elastic actuator","authors":"Ruzhen Pei, Xibin Cao, Cheng Wei","doi":"10.1115/1.4062274","DOIUrl":"https://doi.org/10.1115/1.4062274","url":null,"abstract":"\u0000 In recent years, as robots are frequently required to interact with the external environment, the demand for robot joint flexibility has been increasing. Series elastic actuators (SEAs) are widely used in robot joints as typical compliant actuators. However, the stiffness model based on the classical beam theory has a large error with the reality, which raises the design difficulty. In this paper, the data obtained from finite element analysis is analyzed theoretically. A theoretical model of the stiffness of a typical symmetric elastic element is obtained. The design experiments are verified and the fitting accuracy is 98.27%, which is significantly higher than that of the stiffness model based on classical beam theory. It can be used to design elastic elements that meet specific stiffness requirements.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47185256","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 introduces a low-cost and light weight design for compliant gripping pads to be used for manipulating box-like objects with smaller sized humanoid robots. These pads measure gripping forces and center of pressure. A calibration algorithm is presented for these pads. A hybrid force-alignment-position control system is proposed to regulate the gripping forces and to ensure the surface alignment between the grippers and the object. Limit surface theory is incorporated as a contact friction modeling approach to determine the gripping forces for slippage avoidance. The integrated hardware and software system is demonstrated with a NAO humanoid robot. The pad design and associated software is open sourced. Experiments show the effectiveness of the overall approach.
{"title":"Design, Calibration, and Control of Compliant Force-sensing Gripping Pads for Humanoid Robots","authors":"Yuanfeng Han, Boren Jiang, G. Chirikjian","doi":"10.1115/1.4062273","DOIUrl":"https://doi.org/10.1115/1.4062273","url":null,"abstract":"\u0000 This paper introduces a low-cost and light weight design for compliant gripping pads to be used for manipulating box-like objects with smaller sized humanoid robots. These pads measure gripping forces and center of pressure. A calibration algorithm is presented for these pads. A hybrid force-alignment-position control system is proposed to regulate the gripping forces and to ensure the surface alignment between the grippers and the object. Limit surface theory is incorporated as a contact friction modeling approach to determine the gripping forces for slippage avoidance. The integrated hardware and software system is demonstrated with a NAO humanoid robot. The pad design and associated software is open sourced. Experiments show the effectiveness of the overall approach.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48433655","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}
Yen-hua Lin, Tun Wang, Emmanouil Spyrakos-Papastavridis, Fu Zhongtao, Shuang J. Xu, J. Dai
Reconfigurable robotic hands can constitute one of the future trends of dexterous manipulator design, as they can strike a balance between precision, force exertion, flexibility, and adaptability. However, the feasible manipulation workspace of a reconfigurable robotic hand, the metamorphic hand, is complex as the finger operation planes alter with the reconfigurable palm's motions. Different useful workspace approaches and grasp quality metrics have been introduced, but a precision manipulation workspace (PMW) approach for reconfigurable robotic hands has yet to be presented. This paper presents a hand workspace taxonomy based on previous studies, and a new approach to obtaining a PMW of a robotic hand which satisfies three properties: singularity avoidance, interference avoidance, and force-closure. A grasp quality metric, termed the minimum friction coefficient (MFC), is introduced to indicate the force-closure conditions of a robotic hand's configurations. Unlike the previous grasp quality metrics targeting online grasp planning tasks, this MFC-based measure focuses on the offline design of robotic hands. This method is essential for conducting grasp planning, design optimization, and actuation reduction for reconfigurable robotic hands. Further, the approach is applied to a three-fingered metamorphic hand, and the results are studied thoroughly.
{"title":"Minimum Friction Coefficient-based Precision Manipulation Workspace Analysis of the Three-fingered Metamorphic Hand","authors":"Yen-hua Lin, Tun Wang, Emmanouil Spyrakos-Papastavridis, Fu Zhongtao, Shuang J. Xu, J. Dai","doi":"10.1115/1.4062238","DOIUrl":"https://doi.org/10.1115/1.4062238","url":null,"abstract":"\u0000 Reconfigurable robotic hands can constitute one of the future trends of dexterous manipulator design, as they can strike a balance between precision, force exertion, flexibility, and adaptability. However, the feasible manipulation workspace of a reconfigurable robotic hand, the metamorphic hand, is complex as the finger operation planes alter with the reconfigurable palm's motions. Different useful workspace approaches and grasp quality metrics have been introduced, but a precision manipulation workspace (PMW) approach for reconfigurable robotic hands has yet to be presented. This paper presents a hand workspace taxonomy based on previous studies, and a new approach to obtaining a PMW of a robotic hand which satisfies three properties: singularity avoidance, interference avoidance, and force-closure. A grasp quality metric, termed the minimum friction coefficient (MFC), is introduced to indicate the force-closure conditions of a robotic hand's configurations. Unlike the previous grasp quality metrics targeting online grasp planning tasks, this MFC-based measure focuses on the offline design of robotic hands. This method is essential for conducting grasp planning, design optimization, and actuation reduction for reconfigurable robotic hands. Further, the approach is applied to a three-fingered metamorphic hand, and the results are studied thoroughly.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63503946","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 presents a novel approach for the design and control of a two degrees of freedom (DOF) robotic manipulator driven by one pneumatic artificial muscle (PAM) and one passive spring for each of its DOFs. The required air pressure is supplied to the PAMs using fast switching on/off type pneumatic flow control valves. The proposed control architecture uses a PD controller with a feed-forward term in the outer control loop to correct the position errors using an approximate model of the system dynamics and approximate PAM force-contraction characteristics. An inner pressure regulator loop tracks the reference pressure signals supplied by the outer loop using a pulse width modulation (PWM) scheme to control the pneumatic valves based on the approximated inflation-deflation characteristics for the given pneumatic flow circuit. The proposed controller is unique for PAM actuated robots that simultaneously considers three levels of complications, viz. coupled dynamics of multi-degrees of freedom system, non-linearities in the force-contraction characteristics of PAMs, and nonlinearities involved in the use of on/off type pneumatic flow control valves. Experiments carried out using a laboratory prototype validate the effectiveness of the proposed control scheme.
{"title":"Control of Pneumatic Artificial Muscle actuated Two DOF Robot Using PD Based PWM Strategy with Feed Forward Outer Control Loop","authors":"Sushant Maurya, A. Dutta","doi":"10.1115/1.4062212","DOIUrl":"https://doi.org/10.1115/1.4062212","url":null,"abstract":"\u0000 This work presents a novel approach for the design and control of a two degrees of freedom (DOF) robotic manipulator driven by one pneumatic artificial muscle (PAM) and one passive spring for each of its DOFs. The required air pressure is supplied to the PAMs using fast switching on/off type pneumatic flow control valves. The proposed control architecture uses a PD controller with a feed-forward term in the outer control loop to correct the position errors using an approximate model of the system dynamics and approximate PAM force-contraction characteristics. An inner pressure regulator loop tracks the reference pressure signals supplied by the outer loop using a pulse width modulation (PWM) scheme to control the pneumatic valves based on the approximated inflation-deflation characteristics for the given pneumatic flow circuit. The proposed controller is unique for PAM actuated robots that simultaneously considers three levels of complications, viz. coupled dynamics of multi-degrees of freedom system, non-linearities in the force-contraction characteristics of PAMs, and nonlinearities involved in the use of on/off type pneumatic flow control valves. Experiments carried out using a laboratory prototype validate the effectiveness of the proposed control scheme.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42226870","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}
Z. Lv, F. Xiao, Bao-xing Chen, Ruonan Dong, Zhengshi Liu, Yong Wang
Soft robots can accomplish hand rehabilitation training to ensure better safety and compliance for hand rehabilitation. In this study, a wavy non-rotating soft actuator structure was proposed for hand rehabilitation, and an axial stiffener was added to the main structure of the actuator according to the function of the bamboo fiber. A physical model of the actuator was fabricated using a multistep casting molding method, and the performance of the designed soft actuator was tested experimentally. The results showed that the bending angle and contact force gradually increased with increasing pressure. The average maximum bending angle and contact force can reach 286 ± 14.3 degree and 1.04 ± 0.051 N, with a pressure of 72 kPa. Meanwhile, the bending torques of the soft actuator at various joints (MCP, PIP, DIP) were tested, to verify that it can meet the needs of soft actuators for hand applications. Furthermore, the load lifting of the soft actuator with axial stiffeners can increase by 6 mm on average compared with a soft actuator without axial stiffeners under negative pressure. In conclusion, the pneumatic soft actuator can produce two different motion functions under the action of one cavity. In addition, a soft actuator with an axial stiffener can improve the load capacity under negative pressure. By assembling the actuators, a three-finger gripper was manufactured. The gripper could grasp and lift objects. Therefore, this work provides a new route for the development of pneumatic soft actuators and soft robots, which has efficient driving.
{"title":"Design and performance analysis of wavy non-rotating pneumatic soft actuator","authors":"Z. Lv, F. Xiao, Bao-xing Chen, Ruonan Dong, Zhengshi Liu, Yong Wang","doi":"10.1115/1.4062213","DOIUrl":"https://doi.org/10.1115/1.4062213","url":null,"abstract":"\u0000 Soft robots can accomplish hand rehabilitation training to ensure better safety and compliance for hand rehabilitation. In this study, a wavy non-rotating soft actuator structure was proposed for hand rehabilitation, and an axial stiffener was added to the main structure of the actuator according to the function of the bamboo fiber. A physical model of the actuator was fabricated using a multistep casting molding method, and the performance of the designed soft actuator was tested experimentally. The results showed that the bending angle and contact force gradually increased with increasing pressure. The average maximum bending angle and contact force can reach 286 ± 14.3 degree and 1.04 ± 0.051 N, with a pressure of 72 kPa. Meanwhile, the bending torques of the soft actuator at various joints (MCP, PIP, DIP) were tested, to verify that it can meet the needs of soft actuators for hand applications. Furthermore, the load lifting of the soft actuator with axial stiffeners can increase by 6 mm on average compared with a soft actuator without axial stiffeners under negative pressure. In conclusion, the pneumatic soft actuator can produce two different motion functions under the action of one cavity. In addition, a soft actuator with an axial stiffener can improve the load capacity under negative pressure. By assembling the actuators, a three-finger gripper was manufactured. The gripper could grasp and lift objects. Therefore, this work provides a new route for the development of pneumatic soft actuators and soft robots, which has efficient driving.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46587802","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}
A six-degree of freedom (DOF) two-radii Gough-Stewart Platform (GSP) can be designed to be dynamically isotropic and has been proposed for micro-vibration isolation. In many applications, the torsional mode can be ignored, and a 5-DOF dynamically isotropic, parallel manipulator capable of attenuating three translational (3T) and two rotational (2R) modes are sufficient. In this work, we present the designs of a novel 5-DOF dynamically isotropic parallel manipulator for vibration isolation where the torsion mode can be ignored. We present closed-form solutions in their explicit form, and these are obtained using a geometry-based approach. The first design is based on a modification to the two radii GSP and provides enhanced design flexibility and feasibility. The second design, with the first five decoupled modes, is based on superposing geometrical parameters of two 3-legged dynamically isotropic or decoupled parallel manipulators. It is shown that this design has two translational modes, namely the X, Y modes, which are decoupled from two rotational modes Rot(X), Rot(Y ) and are controlled by two different sets of three legs. This feature can lead to simpler control and less power requirements if active vibration control is chosen. The designs presented in this work include the effect of asymmetry and the payload center of mass variation. The dynamically isotropic and decoupled designs were successfully validated using the finite element software ANSYS®. Experimental results based on a two-radii GSP prototype further validate analytical and simulation results.
{"title":"Design of decoupled and dynamically isotropic parallel manipulators considering five degrees of freedom","authors":"Y. Singh, Nazeer Ahmad, A. Ghosal","doi":"10.1115/1.4062176","DOIUrl":"https://doi.org/10.1115/1.4062176","url":null,"abstract":"\u0000 A six-degree of freedom (DOF) two-radii Gough-Stewart Platform (GSP) can be designed to be dynamically isotropic and has been proposed for micro-vibration isolation. In many applications, the torsional mode can be ignored, and a 5-DOF dynamically isotropic, parallel manipulator capable of attenuating three translational (3T) and two rotational (2R) modes are sufficient. In this work, we present the designs of a novel 5-DOF dynamically isotropic parallel manipulator for vibration isolation where the torsion mode can be ignored. We present closed-form solutions in their explicit form, and these are obtained using a geometry-based approach. The first design is based on a modification to the two radii GSP and provides enhanced design flexibility and feasibility. The second design, with the first five decoupled modes, is based on superposing geometrical parameters of two 3-legged dynamically isotropic or decoupled parallel manipulators. It is shown that this design has two translational modes, namely the X, Y modes, which are decoupled from two rotational modes Rot(X), Rot(Y ) and are controlled by two different sets of three legs. This feature can lead to simpler control and less power requirements if active vibration control is chosen. The designs presented in this work include the effect of asymmetry and the payload center of mass variation. The dynamically isotropic and decoupled designs were successfully validated using the finite element software ANSYS®. Experimental results based on a two-radii GSP prototype further validate analytical and simulation results.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45791849","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}
Weixing Chen, Wen Yu, Tong Xiaochuan, Lin Chaoxiong, Li Jiang, Wang Shuyou, Xie Wei, Mao Lifeng, Xianchao Zhao, W. Zhang, Feng Gao
The ship-borne Stewart platform can compensate for the six-degree-of-freedom motion generated by the ship, which improves the reliability and safety of offshore operations and increases the executable window period. The heavy and off-center load of the gangway significantly influences the high-precision compensation control of the platform. Besides, the gangway assembled on the platform vibrates easily due to its low natural frequency which requires high dynamic performance of the compensating. To deal with the problem mentioned, the modal space control strategy is introduced to fully consider the inertia characteristics. Firstly, based on Kane's method, the complete dynamic model considering the ship's motion and actuator inertia is established. Then, the modal space PD controller (MSPDC) and the modal space sliding mode controller (MSSMC) are designed based on modal theory. Finally, simulations are carried out to show the advantages of the proposed model and the advantages of proposed controllers in compensation accuracy and anti-interference ability. Furthermore, The Significant Compensation Rate (SCR) is proposed to evaluate the six-DOF compensation accuracy. Compared with the PD controller with gravity compensation (PDCGC), the position SCR of MSSMC is increased from 95.37 % to 99.28 %, and the angle SCR from 85.57 % to 99.65 %.
{"title":"Dynamics modeling and modal space control strategy of ship-borne Stewart platform for wave compensation","authors":"Weixing Chen, Wen Yu, Tong Xiaochuan, Lin Chaoxiong, Li Jiang, Wang Shuyou, Xie Wei, Mao Lifeng, Xianchao Zhao, W. Zhang, Feng Gao","doi":"10.1115/1.4062177","DOIUrl":"https://doi.org/10.1115/1.4062177","url":null,"abstract":"\u0000 The ship-borne Stewart platform can compensate for the six-degree-of-freedom motion generated by the ship, which improves the reliability and safety of offshore operations and increases the executable window period. The heavy and off-center load of the gangway significantly influences the high-precision compensation control of the platform. Besides, the gangway assembled on the platform vibrates easily due to its low natural frequency which requires high dynamic performance of the compensating. To deal with the problem mentioned, the modal space control strategy is introduced to fully consider the inertia characteristics. Firstly, based on Kane's method, the complete dynamic model considering the ship's motion and actuator inertia is established. Then, the modal space PD controller (MSPDC) and the modal space sliding mode controller (MSSMC) are designed based on modal theory. Finally, simulations are carried out to show the advantages of the proposed model and the advantages of proposed controllers in compensation accuracy and anti-interference ability. Furthermore, The Significant Compensation Rate (SCR) is proposed to evaluate the six-DOF compensation accuracy. Compared with the PD controller with gravity compensation (PDCGC), the position SCR of MSSMC is increased from 95.37 % to 99.28 %, and the angle SCR from 85.57 % to 99.65 %.","PeriodicalId":49155,"journal":{"name":"Journal of Mechanisms and Robotics-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46712594","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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