The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Xiaohui Xiao - One of the best experts on this subject based on the ideXlab platform.
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ICRA - Mechanical design of a compact Serial Variable Stiffness Actuator (SVSA) based on Lever Mechanism
2017 IEEE International Conference on Robotics and Automation (ICRA), 2017Co-Authors: Yubing Zhang, Cong Zhang, Xiaohui XiaoAbstract:Compliant actuator is widely accepted for physical human-robot interaction due to its safety aspect, dynamic performance improvements and energy saving abilities. In this paper, based on the variable ratio Lever Mechanism, a new kind of Serial Variable Stiffness Actuator (SVSA) is proposed by using an Archimedean Spiral Relocation Mechanism (ASRM) to change the position of the pivot, implementing large range of adjustable stiffness. The ASRM introduced here makes the SVSA design has continuous stiffness adjustment ability and simply mechanical structure. Within the Variable Stiffness Mechanism (VSM), two linear springs are assembled antagonistically on a spring shaft. Their displacements are perpendicular to the output link to transmit the spring force more efficiently. Stiffness modeling and analysis of the SVSA are carried out to cover large deflection angle. The physical implementation of the SVSA shows that the output stiffness of the VSM is changed from 1.72 to 150.56 Nm/rad using a linear spring with stiffness 1882 N/m, working range covered from 0 to 360 °. Control experiments also proved the wide range of stiffness adjustment ability of the SVSA.
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Mechanical design of a compact Serial Variable Stiffness Actuator (SVSA) based on Lever Mechanism
2017 IEEE International Conference on Robotics and Automation (ICRA), 2017Co-Authors: Yubing Zhang, Cong Zhang, Xiaohui XiaoAbstract:Compliant actuator is widely accepted for physical human-robot interaction due to its safety aspect, dynamic performance improvements and energy saving abilities. In this paper, based on the variable ratio Lever Mechanism, a new kind of Serial Variable Stiffness Actuator (SVSA) is proposed by using an Archimedean Spiral Relocation Mechanism (ASRM) to change the position of the pivot, implementing large range of adjustable stiffness. The ASRM introduced here makes the SVSA design has continuous stiffness adjustment ability and simply mechanical structure. Within the Variable Stiffness Mechanism (VSM), two linear springs are assembled antagonistically on a spring shaft. Their displacements are perpendicular to the output link to transmit the spring force more efficiently. Stiffness modeling and analysis of the SVSA are carried out to cover large deflection angle. The physical implementation of the SVSA shows that the output stiffness of the VSM is changed from 1.72 to 150.56 Nm/rad using a linear spring with stiffness 1882 N/m, working range covered from 0 to 360°. Control experiments also proved the wide range of stiffness adjustment ability of the SVSA.
Yubing Zhang - One of the best experts on this subject based on the ideXlab platform.
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ICRA - Mechanical design of a compact Serial Variable Stiffness Actuator (SVSA) based on Lever Mechanism
2017 IEEE International Conference on Robotics and Automation (ICRA), 2017Co-Authors: Yubing Zhang, Cong Zhang, Xiaohui XiaoAbstract:Compliant actuator is widely accepted for physical human-robot interaction due to its safety aspect, dynamic performance improvements and energy saving abilities. In this paper, based on the variable ratio Lever Mechanism, a new kind of Serial Variable Stiffness Actuator (SVSA) is proposed by using an Archimedean Spiral Relocation Mechanism (ASRM) to change the position of the pivot, implementing large range of adjustable stiffness. The ASRM introduced here makes the SVSA design has continuous stiffness adjustment ability and simply mechanical structure. Within the Variable Stiffness Mechanism (VSM), two linear springs are assembled antagonistically on a spring shaft. Their displacements are perpendicular to the output link to transmit the spring force more efficiently. Stiffness modeling and analysis of the SVSA are carried out to cover large deflection angle. The physical implementation of the SVSA shows that the output stiffness of the VSM is changed from 1.72 to 150.56 Nm/rad using a linear spring with stiffness 1882 N/m, working range covered from 0 to 360 °. Control experiments also proved the wide range of stiffness adjustment ability of the SVSA.
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Mechanical design of a compact Serial Variable Stiffness Actuator (SVSA) based on Lever Mechanism
2017 IEEE International Conference on Robotics and Automation (ICRA), 2017Co-Authors: Yubing Zhang, Cong Zhang, Xiaohui XiaoAbstract:Compliant actuator is widely accepted for physical human-robot interaction due to its safety aspect, dynamic performance improvements and energy saving abilities. In this paper, based on the variable ratio Lever Mechanism, a new kind of Serial Variable Stiffness Actuator (SVSA) is proposed by using an Archimedean Spiral Relocation Mechanism (ASRM) to change the position of the pivot, implementing large range of adjustable stiffness. The ASRM introduced here makes the SVSA design has continuous stiffness adjustment ability and simply mechanical structure. Within the Variable Stiffness Mechanism (VSM), two linear springs are assembled antagonistically on a spring shaft. Their displacements are perpendicular to the output link to transmit the spring force more efficiently. Stiffness modeling and analysis of the SVSA are carried out to cover large deflection angle. The physical implementation of the SVSA shows that the output stiffness of the VSM is changed from 1.72 to 150.56 Nm/rad using a linear spring with stiffness 1882 N/m, working range covered from 0 to 360°. Control experiments also proved the wide range of stiffness adjustment ability of the SVSA.
Junyoung Moon - One of the best experts on this subject based on the ideXlab platform.
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IROS - Design of Compact Variable Gravity Compensator (CVGC) Based on Cam and Variable Pivot of a Lever Mechanism
2019 IEEE RSJ International Conference on Intelligent Robots and Systems (IROS), 2019Co-Authors: Junyoung MoonAbstract:In this paper, we propose a new compact variable gravity compensation Mechanism (CVGC). The CVGC can be used to generate gravity compensation torque by using the cam and Lever Mechanism and can also amplify the target gravity compensation torque by varying the pivot point of the Lever. The feature of variable gravity compensation is very useful to the mobile platform, which needs to handle unstandardized tasks with a high variation of the workpiece weight. The proposed CVGC has many advantages. Most importantly, it is designed as a compact, independent one-piece structure and is lightweight, meaning it can easily be used as a mobile platform with a simple modification. The CVGC can also have a full range of compensation angle $(360^{\circ})$, so it does not restrict any of the original workspaces of the target platform when it is installed. First, the Mechanism concept and details are explained. Next, the mechanics of the prototype for force analysis are presented. Based on these mechanics and cam theory, the methodology of the cam profile design is presented. Finally, the performance of variable gravity compensation is verified through experiments that compare the designed and measured gravity compensation torque. The verification test shows adequate performance, as we had hoped, which shows potential for the development of the CVGC.
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Design of Compact Variable Gravity Compensator (CVGC) Based on Cam and Variable Pivot of a Lever Mechanism
2019 IEEE RSJ International Conference on Intelligent Robots and Systems (IROS), 2019Co-Authors: Junyoung MoonAbstract:In this paper, we propose a new compact variable gravity compensation Mechanism (CVGC). The CVGC can be used to generate gravity compensation torque by using the cam and Lever Mechanism and can also amplify the target gravity compensation torque by varying the pivot point of the Lever. The feature of variable gravity compensation is very useful to the mobile platform, which needs to handle unstandardized tasks with a high variation of the workpiece weight. The proposed CVGC has many advantages. Most importantly, it is designed as a compact, independent one-piece structure and is lightweight, meaning it can easily be used as a mobile platform with a simple modification. The CVGC can also have a full range of compensation angle (360°), so it does not restrict any of the original workspaces of the target platform when it is installed. First, the Mechanism concept and details are explained. Next, the mechanics of the prototype for force analysis are presented. Based on these mechanics and cam theory, the methodology of the cam profile design is presented. Finally, the performance of variable gravity compensation is verified through experiments that compare the designed and measured gravity compensation torque. The verification test shows adequate performance, as we had hoped, which shows potential for the development of the CVGC.
Darwin G. Caldwell - One of the best experts on this subject based on the ideXlab platform.
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Energy efficient actuators with adjustable stiffness: a review on AwAS, AwAS-II and CompACT VSA changing stiffness based on Lever Mechanism
Industrial Robot-an International Journal, 2015Co-Authors: Amir Jafari, Nikos G. Tsagarakis, Darwin G. CaldwellAbstract:Purpose This paper aims to discuss, analyze and compare members of a group of actuators with adjustable stiffness, namely: AwAS, AwAS-II and CompACT variable stiffness actuator (VSA) developed at Italian Institute of Technology (IIT). Design/methodology/approach These actuators are among series type of VSAs where one main motor is dedicated for link positioning and a secondary motor, in series with the first one, regulates the output link stiffness. Regulating the stiffness in this group of actuators is based on the Lever concept. Initially, springs were moved along the Lever to tune the stiffness while in the later versions stiffness was regulated through relocating pivot point along the Lever. Findings This paper discusses how different Mechanisms have been employed in realization of the Lever concept in these actuators and what are the advantages and disadvantages of each realization. Practical implications Today’s robots are not supposed to be solid, isolated and rigid anymore but rather adaptive, cooperative and compliant entities in our daily life. The new attitudes demand for novel technologies substantially different from those developed for industrial domains both at the hardware and the software levels. This work presents latest three state-of-the-art actuators, developed at IIT, which are great answers to the needs of tomorrow’s robot. Originality/value These novel actuators are really ready for commercial exploitation, as they are compact and reliable. The main novelty is based on employing concept of Lever Mechanism for stiffness regulation. They have been designed and manufactured in a very professional and optimized way.
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A New Actuator With Adjustable Stiffness Based on a Variable Ratio Lever Mechanism
IEEE ASME Transactions on Mechatronics, 2014Co-Authors: Amir Jafari, Nikos G. Tsagarakis, Irene Sardellitti, Darwin G. CaldwellAbstract:This paper presents the actuator with adjustable stiffness (AwAS-II), an enhanced version of the original realization AwAS. This new variable stiffness actuator significantly differs from its predecessor on the Mechanism used for the stiffness regulation. While AwAS tunes the stiffness by regulating the position of the compliant elements along the Lever arm, AwAS-II changes the position of the Lever's pivot point. As a result of the new principle, AwAS-II can change the stiffness in a much broader range (from zero to infinity) even by using softer springs and shorter Lever arm, compared to AwAS. This makes the setup of AwAS-II more compact and lighter and improves the stiffness regulation response. To evaluate the aptitude of the fast stiffness adjustment, experiments on reproducing the stiffness profile of the human ankle during the stance phase of a normal walking gait are conducted. Results indicate that AwAS-II is capable of reproducing an interpolated stiffness profile of the ankle while providing a net positive work and thus a sufficient amount of energy as required for the toe-off.
Cong Zhang - One of the best experts on this subject based on the ideXlab platform.
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ICRA - Mechanical design of a compact Serial Variable Stiffness Actuator (SVSA) based on Lever Mechanism
2017 IEEE International Conference on Robotics and Automation (ICRA), 2017Co-Authors: Yubing Zhang, Cong Zhang, Xiaohui XiaoAbstract:Compliant actuator is widely accepted for physical human-robot interaction due to its safety aspect, dynamic performance improvements and energy saving abilities. In this paper, based on the variable ratio Lever Mechanism, a new kind of Serial Variable Stiffness Actuator (SVSA) is proposed by using an Archimedean Spiral Relocation Mechanism (ASRM) to change the position of the pivot, implementing large range of adjustable stiffness. The ASRM introduced here makes the SVSA design has continuous stiffness adjustment ability and simply mechanical structure. Within the Variable Stiffness Mechanism (VSM), two linear springs are assembled antagonistically on a spring shaft. Their displacements are perpendicular to the output link to transmit the spring force more efficiently. Stiffness modeling and analysis of the SVSA are carried out to cover large deflection angle. The physical implementation of the SVSA shows that the output stiffness of the VSM is changed from 1.72 to 150.56 Nm/rad using a linear spring with stiffness 1882 N/m, working range covered from 0 to 360 °. Control experiments also proved the wide range of stiffness adjustment ability of the SVSA.
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Mechanical design of a compact Serial Variable Stiffness Actuator (SVSA) based on Lever Mechanism
2017 IEEE International Conference on Robotics and Automation (ICRA), 2017Co-Authors: Yubing Zhang, Cong Zhang, Xiaohui XiaoAbstract:Compliant actuator is widely accepted for physical human-robot interaction due to its safety aspect, dynamic performance improvements and energy saving abilities. In this paper, based on the variable ratio Lever Mechanism, a new kind of Serial Variable Stiffness Actuator (SVSA) is proposed by using an Archimedean Spiral Relocation Mechanism (ASRM) to change the position of the pivot, implementing large range of adjustable stiffness. The ASRM introduced here makes the SVSA design has continuous stiffness adjustment ability and simply mechanical structure. Within the Variable Stiffness Mechanism (VSM), two linear springs are assembled antagonistically on a spring shaft. Their displacements are perpendicular to the output link to transmit the spring force more efficiently. Stiffness modeling and analysis of the SVSA are carried out to cover large deflection angle. The physical implementation of the SVSA shows that the output stiffness of the VSM is changed from 1.72 to 150.56 Nm/rad using a linear spring with stiffness 1882 N/m, working range covered from 0 to 360°. Control experiments also proved the wide range of stiffness adjustment ability of the SVSA.