Magnetorheological torque transmission devices with permanent magnets

Böse, Holger; Gerlach, Thomas; Ehrlich, Johannes

doi:10.1088/1742-6596/412/1/012050

Cited by 17 publications

(19 citation statements)

References 1 publication

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“…The best reported performance is provided by [17]. This clutch weighed 4.5 kg, produced 75 N·m of torque without any gearing, and consumed at least 1 W of power (estimated from similar devices [15][16][17][18]). Comparable performance would be achieved by stacking electroadhesive clutches in parallel and adding another set of electrodes to each carbon fiber shim.…”

Section: Discussionmentioning

confidence: 99%

“…Electromagnetic clutches are a common choice [11,14], featuring fast activation and moderate torque density, but also requiring continuous electrical power to stay active. Magnetorheological clutches can produce large torques without gearing [15][16][17][18], but are heavy and require continuous electrical power to remain active. Mechanical latches have high torque density and require no energy to stay active [2,3,5] but typically can only engage or disengage under special conditions particular to one application.…”

Section: Introductionmentioning

confidence: 99%

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A lightweight, low-power electroadhesive clutch and spring for exoskeleton actuation

Diller

Majidi

Collins

2016

2016 IEEE International Conference on Robotics and Automation (ICRA)

111

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Clutches can be used to enhance the functionality of springs or actuators in robotic devices. Here we describe a lightweight, low-power clutch used to control spring engagement in an ankle exoskeleton. The clutch is based on electrostatic adhesion between thin electrode sheets coated with a dielectric material. Each electrode pair weighs 1.5 g, bears up to 100 N, and changes states in less than 30 ms. We placed clutches in series with elastomer springs to allow control of spring engagement, and placed several clutched springs in parallel to discretely adjust stiffness. By engaging different numbers of springs, the system produced six different levels of stiffness. Force at peak displacement ranged from 14 to 501 N, and the device returned 95% of stored mechanical energy. Each clutched spring element weighed 26 g. We attached one clutched spring to an ankle exoskeleton and used it to engage the spring only while the foot was on the ground during 150 consecutive walking steps. Peak torque was 7.3 N·m on an average step, and the device consumed 0.6 mW of electricity. Compared to other electrically-controllable clutches, this approach results in three times higher torque density and two orders of magnitude lower power consumption per unit torque. We anticipate this technology will be incorporated into exoskeletons that tune stiffness online and into new actuator designs that utilize many lightweight, lowpower clutches acting in concert.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A lightweight, low-power electroadhesive clutch and spring for exoskeleton actuation

Diller

Majidi

Collins

2016

2016 IEEE International Conference on Robotics and Automation (ICRA)

111

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“…The most frequent uses of ER and MR fluids are in devices such as clutches and brakes (Olszak et al, 2016a;Raju et al, 2016;Gao et al, 2017). To achieve the assumed characteristics of clutches and brakes with ER and MR fluids, their architectures are taken into consideration by analyzing the shape and position of working space (Avraam et al, 2010), the way of producing the electric or magnetic field (Takesue et al, 2003;Böse et al, 2013;Sohn et al, 2018) as well as thermal working conditions (Chen et al, 2015;Song et al, 2018). Additionally taken into consideration are the smart fluids used for construction of clutches and brakes with ER and MR, mainly their composition (Sarkar and Hirani, 2013;Kumbhar et al, 2015;Mangal et al, 2016) and durability (Olszak et al, 2016b;Kim et al, 2017;Ziabska et al, 2017).…”

Section: Literature Studymentioning

confidence: 99%

Selection of Materials Used in Viscous Clutch With ER Fluid Working in Special Conditions

et al. 2019

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This article presents considerations regarding materials used to fabricate a hydraulic clutch with an ER fluid operating in non-standard working conditions. The hydraulic clutch was a subassembly of the device used for exerting a controlled force on the stationary object. This clutch was driven by an electric motor. The force was controlled by changing the shear stresses in the ER fluid. Shear stresses were changed in two ways: by changing the angular velocity of the electric motor and by changing the high voltage applied to the electrodes located on the driving part and the driven part of the clutch. The increase in these stresses caused an increase in the torque transmitted and an increase in the pressure force. In order to construct the clutch, mathematical models based on the Bingham model were developed, which took into account the influence of temperature and humidity on the shear stress in the ER fluid, allowing calculation of the clutch performance. In addition, numerical calculations of the temperature distribution inside the clutch were carried out using the ANSYS program because of the intense heat generation during the clutch operation. The developed mathematical models were used to optimize the clutch. The aim of the optimization was to obtain a high transmitted torque with small dimensions of the clutch, taking into account the thermal capacity of the clutch. Based on the optimization results, a prototype of a hydraulic clutch with an ER fluid was designed and made, assuming that for metal materials their anti-corrosion properties are the most important, since the presence of conductive metal oxides causes electrical breakdowns. The plastics used in the clutch prototype were mainly evaluated for insulating properties and high temperature resistance. When choosing the ER fluid, its sensitivity to temperature and humidity as well as durability were taken into account. The clutch prototype has been tested on a specially built test rig. The test results confirmed the proper selection of both construction materials and ER fluids. Based on the results of these tests, guidelines for the construction of clutches with ER fluids were formulated.

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“…Magnetorheological Fluids (MRF) have been used in controllable devices for many years. Typical applications include damper systems [8], clutches for torque transfer [9,10] and braking systems [11].…”

Section: Prior Artmentioning

confidence: 99%

Controllable Magnetoactive Polymer Conduit

Diermeier¹,

Sindersberger²,

Krenkel³

et al. 2018

TOMEJ

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Objective: Magneto-active Polymers (MAP) are smart materials whose mechanical characteristics, such as elastic and shear moduli, may be controllable by means of an externally applied magnetic field. Methods: Various additives may be used to influence the characteristics of the polymer matrix whilst a suspension of soft and/or hard magnetic particles determine the magnetic properties of the composite. Both pre-cure and post-cure magnetization is possible. Results: A range of control strategies have been investigated for evaluation of the system using fluids of differing kinematic viscosity. Conclusion: Depending on the degree of magnetic field homogeneity, magneto-deformation and magnetostriction contribute to MAP actuation. This paper presents a novel application in the form of a peristaltic MAP tube system, applicable to flow control and pumping of hemorheological fluids in blood circulatory systems for biomedical research purposes.

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Magnetorheological torque transmission devices with permanent magnets

Cited by 17 publications

References 1 publication

A lightweight, low-power electroadhesive clutch and spring for exoskeleton actuation

A lightweight, low-power electroadhesive clutch and spring for exoskeleton actuation

Selection of Materials Used in Viscous Clutch With ER Fluid Working in Special Conditions

Controllable Magnetoactive Polymer Conduit

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