The vsaUT-II: A novel rotational variable stiffness actuator

Groothuis, Stefan S.; Rusticelli, Giacomo; Zucchelli, Andrea; Stramigioli, Stefano; Carloni, Raffaella

doi:10.1109/icra.2012.6224868

Cited by 63 publications

(58 citation statements)

References 17 publications

(30 reference statements)

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“…As is illustrated in Figure 8(c), the movable pulley rod (10) and the movable baffle (7) are used to ensure that the tendons always maintain contact with the driving pulley. The related design and kinematic relationship are shown in Figure 9.…”

Section: Mathematical Modelling Of the First Vsamentioning

confidence: 99%

“…Some designs rely on changing the transmission ratio between the output and the internal elastic elements. The AwAS-II [5], CompAct-VSA [6], CompAct-ARS [7], HDAU [8], the vsaUT [9], the vsaUT-II [10], and the mVSA-UT [11] use a lever arm of variable effective length to regulate the transmission ratio. As is elaborated in [12], the output stiffness of these variable stiffness actuators can be changed without any energy injection into or extraction from the internal elastic elements.…”

Section: Introductionmentioning

confidence: 99%

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Conceptual Design and Analysis of Four Types of Variable Stiffness Actuators Based on Spring Pretension

Guo

Tian

2015

International Journal of Advanced Robotic Systems

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The variable stiffness actuator (VSA) is an open research field. This paper introduces the conceptual design and analysis of four types of novel variable stiffness actuators (VSAs). The main novelty of this paper is focused on the convenience control of the torque and stiffness of the actuator. We do not need to design complicated control strategies to achieve the desired actuating torque and output stiffness. This feature is beneficial for real-time control. In order to achieve this advantage, three types of approximate quadratic springs and four types of stiffness regulation mechanisms are presented. For the first VSA, the relationship between the output stiffness and angular deflection is close to linear, and the fitted quadratic spring is easy to implement and compact. For the second VSA, the output stiffness is only related to the working radius, and the relationship between the exerted torque and angular deflection is linear. For the third VSA, two equivalent quadratic torsion springs are used. Compared with the existing quadratic torsion springs, the design method is simple and the structure size is compact. The stiffness and torque is a linear function of the kinematic parameters of the VSA. The novelty of the fourth VSA is the use of the tension spring set. The approximate quadratic tension spring is compact and easy to implement. The relationship between the output stiffness and the angular deflection is fairly linear. The conceptual layouts and working principles are elaborated for the four actuators. The characteristics of torque and stiffness of the VSAs are presented, and the mechanical solutions are illustrated.

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Section: Mathematical Modelling Of the First Vsamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Conceptual Design and Analysis of Four Types of Variable Stiffness Actuators Based on Spring Pretension

Guo

Tian

2015

International Journal of Advanced Robotic Systems

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“…두 개의 모터가 비 선형성의 탄성요소로 연결되어 장력을 조절하는 방식을 채택한 MACCEPA, (6) VSA-II (7) 및 VSAJoint, (2) 판 스프링을 활용한 VSJ, (8) 가변 모멘트 팔 기반의 HDAU, (9) AwAS, (10) AwAS-II (11) 및 vsaUT-II (12) …”

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Small-Sized Variable Stiffness Actuator Module Based on Adjustable Moment Arm

Yu¹,

Song²

2013

Transactions of the Korean Society of Mechanical Engineers A

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In recent years, variable stiffness actuation has attracted much attention because interaction between a robot and the environment is increasingly required for various robot tasks. Several variable stiffness actuators (VSAs) have been developed; however, they find limited applications owing to their size and weight. For realizing their widespread use, we developed a compact and lightweight mini-VSA. The mini-VSA consists of a control module based on an adjustable moment arm mechanism and a drive module with two motors. By controlling the relative motion of cams in the control module, the position and stiffness can be simultaneously controlled. Experimental results are presented to show its ability to change stiffness.

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“…Examples include robotic hands, where the elastic elements are used to perform a stable grasp [1][2][3], flying robots, in order to estimate the pitch torques generated by wings during flapping [4] and robotic snakes, for estimating ground contact forces [5]. Furthermore elastic elements are key components of Series Elastic Actuators (SEAs) [6][7][8][9], Variable Stiffness Actuators (VSAs) [10][11][12][13][14][15][16][17][18] and, more generally, of Variable Impedance Actuators (VIAs) [19], where damping can also be adjusted by properly controlling the device. In this field, a seminal work is that of Fasse et al [20], where an electromagnetic variable impedance actuator is demonstrated, capable of exerting a torque much higher than that of the prototype described in this paper.…”

Section: Introductionmentioning

confidence: 99%

Design, Development and Scaling Analysis of a Variable Stiffness Magnetic Torsion Spring

Sudano

Accoto

Zollo

et al. 2013

International Journal of Advanced Robotic Systems

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In this paper we report on the design, modeling, experimental testing and scaling analysis of a novel MAgnetic Variable stiffnEess spRIng-Clutch (MAVERIC) device, which may be used as the elastic element of Variable Stiffness Actuators (VSAs). The device, comprising two co-axial diametrically magnetized hollow cylinders, has two degrees of freedom: a rotation of the two cylinders around the common axis and a relative translation along the same axis. For small rotations, the torque arising from the magnetic interaction of the two cylinders is almost linearly proportional to their relative rotation, as in mechanical torsion springs. In addition, the stiffness of the equivalent spring can be varied continuously from a maximum value down to exactly zero by changing the axial overlap of the two cylinders. In this way the proposed device can be used both as a clutch (i.e., perfectly compliant element) and as a variable stiffness torsion spring. A prototype, designed after magnetostatic FEM simulations, has been built and experimentally characterized. The developed MAVERIC has an experimentally determined maximum transmissible torque of 109.81 mN m, while the calculated maximum stiffness is 110.2 mN m rad −1 . The amplitude of the torque-angle characteristic can be tuned linearly with a sensitivity of 12.63 mN m mm −1 rad −1 . Further simulations have been computed parameterizing the geometry and the number of pole pairs of the magnets.The maximum torque density reached for one pole pair is 47.21 · 10 3 N m m −3 , whereas for a fixed geometry similar to that of the developed prototype, the maximum torque is reached for seven pole pairs. Overall, compared to mechanical springs, MAVERIC has no fatigue or overloading issues. Compared to other magnetic couplers, torsion stiffness can be varied continuously from a maximum value down to exactly zero, when the device acts as a disengaged clutch, disconnecting the load from the actuator.

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The vsaUT-II: A novel rotational variable stiffness actuator

Cited by 63 publications

References 17 publications

Conceptual Design and Analysis of Four Types of Variable Stiffness Actuators Based on Spring Pretension

Conceptual Design and Analysis of Four Types of Variable Stiffness Actuators Based on Spring Pretension

Small-Sized Variable Stiffness Actuator Module Based on Adjustable Moment Arm

Design, Development and Scaling Analysis of a Variable Stiffness Magnetic Torsion Spring

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