Active Variable Stiffness Elastic Actuator: design and application for safe physical human-robot interaction

Wang, Ren-Jeng; Huang, Han-Pang

doi:10.1109/robio.2010.5723537

Cited by 12 publications

(11 citation statements)

References 13 publications

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“…To resolve these limitations, a mechanism to engage or vary the stiffness is necessary. Although clutch mechanisms [20], [21] or variable compliance mechanisms [8], [9], [11], [12], [13], [14], [15] in series to the actuator in the drive train are well established, low cost, low-complexity solutions of clutched parallel elastic actuators (CPEA) have so far not been established. We presented a prototype for such a CPEA and a simple trigger-based control of it for rebounding tasks in legged locomotion.…”

Section: Discussion and Future Plansmentioning

confidence: 99%

“…To overcome this limitation of PEAs, [1] suggest further investigation of "mechanisms with position-dependent clutch function". And although strategies for engagement and disengagement of elasticities [7], [8], [9], [10], [11], [12], [13], [14], [15] have been proposed, a low-cost, low-complexity, and low-weight compact solution for a clutched parallel elastic actuator (CPEA) has not been established.…”

Section: Introductionmentioning

confidence: 99%

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A clutched parallel elastic actuator concept: Towards energy efficient powered legs in prosthetics and robotics

Haeufle

Taylor

Schmitt

et al. 2012

2012 4th IEEE RAS &Amp; EMBS International Conference on Biomedical Robotics and Biomechatronics (BioRob)

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Parallel passive-elastic elements can reduce the energy consumption and torque requirements for motors in powered legged systems. However, the hardware design for such combined actuators is challenged by the need to engage and disengage the parallel elasticity depending on the gait phase. Although clutches in the drive train are often proposed, compact and low cost solutions of clutched parallel elastic actuators have so far not been established. Here we present the design and control of an initial prototype for a parallel elastic actuator. The actuator combines a DC motor with a parallel spring that is engaged and disengaged by a commercially available, compact and low-cost electric clutch. In experiments that mimic the torque and motion patterns of knee extensor muscles in human rebounding tasks we find that the parallel spring in the prototype reduces the energy consumption of the actuator by about 80% and the peak torque requirement for the DC motor by about 66%. In addition, we find that a simple trigger-based control can reliably engage and disengage the electric clutch during the motion, allowing the spring to support the motor in rebound, to remove stored energy from the system as necessary for stopping, and to virtually disappear at the actuator output level. On the other hand, the hardware experiments also reveal that our initial design limits the precision in the torque control, and we propose specific improvements to overcome these limitations.

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Section: Discussion and Future Plansmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A clutched parallel elastic actuator concept: Towards energy efficient powered legs in prosthetics and robotics

Haeufle

Taylor

Schmitt

et al. 2012

2012 4th IEEE RAS &Amp; EMBS International Conference on Biomedical Robotics and Biomechatronics (BioRob)

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“…In AVSER [12], VsaMGR [13], VSJ [14], VSR-Joint [15] and other variable stiffness joints use a leaf spring to change the stiffness of the joint by changing the extended length of the leaf spring. Due to limitations of the structure, the adjustment range of the stiffness in this method is small.…”

Section: Introductionmentioning

confidence: 99%

A Design and Modeling of the Bionic Variable Stiffness Unit Based on the Elbow Joint

Cheng

Liu

2018

2018 3rd International Conference on Robotics and Automation Engineering (ICRAE)

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Due to problems of slow response speed and complex mechanisms, the application of variable stiffness joints is limited. The variable stiffness element can be divided into the part with variable stiffness and the part with adjustable external force point. The variable stiffness part adopts the lever principle and changes the stiffness of the joint by changing the length of the lever arm. The external force adjustment part adopts the two-stage four-bar mechanism, which transforms the gravity of the object into the horizontal movement of the slider on the guide rail. The response speed of the unit is greatly improved by the use of the pure mechanism. It is ensured that the stiffness of the variable stiffness unit can be adjusted at the same time with smaller size and a wide range of stiffness adjustment. Based on the elbow joint, a bionic variable stiffness unit is proposed. It can automatically change the stiffness according to the different grasping of a weight, which is same as the human arm. On the basic of/According to the derivation of the Variable Stiffness Unit mathematical model, the three-dimensional model of the Variable Stiffness unit is drawn.

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“…Other studies those proposed novel torsional spring shapes provide valuable references for new spring designs from scratch. In [6][7][8] a long and thin beam is utilized as an elastic component to give the actuator compliance. Although it is feasible, since the amount of the elasticity is positively correlated with the length of the beam, the actuator is large or with low compliance if keep it compact.…”

Section: Introductionmentioning

confidence: 99%

“…where K is the constant stiffness of the spring, and we also have 0 e e r r (6) where e r is the end radius of the helix curve.…”

mentioning

confidence: 99%

The Optimum Design of Torsional Spring for Series Elastic Actuator

Lin

Zhao

Han

et al. 2017

2017 IEEE 7th Annual International Conference on CYBER Technology in Automation, Control, and Intelligent Systems (CYBER)

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The use of series elastic actuators (SEA) in the applications with presence of human machine coupling has received extensive attention. One of the important research questions is how to design more efficient and compact flexible joints using physical springs. In this research work, we propose an optimization method for designing a planar torsional spiral spring with a shape of Archimedes curve. To define this optimization problem, the objective function and the constraint condition equations are put forward. We set the minimization of final volume, diameter and height of the spring as the optimization goal, the fixed stiffness of the spring as an equality constraint, the maximum deformation angle and the maximum stress of the spring when it reaches this angle, which should be less than the allowable, as two inequality constraints. To solve this optimization problem, the Spiral Dynamics Algorithm (SDA) is utilized to obtain the optimal parameter vector for this nonlinear constrained optimization problem. To validate the optimal result, a simulation with finite element analysis (FEA) is carried out, and the result shows that the obtained solution vector meets the design goal.

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Active Variable Stiffness Elastic Actuator: design and application for safe physical human-robot interaction

Cited by 12 publications

References 13 publications

A clutched parallel elastic actuator concept: Towards energy efficient powered legs in prosthetics and robotics

A clutched parallel elastic actuator concept: Towards energy efficient powered legs in prosthetics and robotics

A Design and Modeling of the Bionic Variable Stiffness Unit Based on the Elbow Joint

The Optimum Design of Torsional Spring for Series Elastic Actuator

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